tips for fuel economy

allana13

Active member
Joined
Jan 27, 2011
Location
England
TDI
VW Golf
That’s is very informative Mike

Many thanks for that.

Couple of questions What is Pulse and Gliding a bit more detail on that please.

Can we have 44/46 PSI without affecting the tyre? I have good years on mine. I am looking to chage them to all weather tyres. Any recommendation.
I have the standard VW Sports Alloys on MK4 Golfs

Thanks



I'm at a proper computer now :) This is an adapted version of something I posted on a different forum:


Note that since the weather is now subzero, the good tanks from summer are unlikely to be repeated until next may or so when the temperatures recover.

Here's the full list of techniques I use - the really important ones are in bold.

* The single most important thing is to keep your motorway cruising speed down to reduce aero drag. I usually stick to 60mph (often I am pulse&gliding between 55 and 60 where traffic, terrain & wind direction permits).
* Make sure the car is in good condition (the correct oil, clean filters, brakes not binding, etc).
* Tyres @ high pressure - I use 44/46 psi, but keep an eye on the centre wear since cheapo tyres will bulge & wear unevenly if at this pressure. Good tyres can handle the pressure fine. The tyres should never be allowed to drop below their proper pressure.
* Climate control & heater off unless absolutely essential (e.g., if it is near freezing you should have the heater on). But turn on the climate control briefly once per tank, after the engine has fully warmed up. This keeps the seals good.
* Keep windows shut above 35mph (not really relevant at the moment since they wouldn't be open in the first place!!!)
* Keep RPM low (but only when engine load is also low). When I'm going at a steady 30 on the flat I'm in 5th at around 1000 rpm. If you need to slow down / speed up / go up an incline you will need to drop a gear or two otherwise you will be overloading ('lugging') the engine. As stated elsewhere you will also need to thrash the car sometimes in order to clean out the coke. Also be aware that low-rpm/high-load will stress your clutch & transmission, so don't forget to change down using the throttle.
* Be aware of wind speed & direction and change your cruising speed appropriately (it affects aero drag). You can go faster with a tailwind but drop your cruising speed if there is a headwind.
* Keep an eye on engine temperature, be very gentle until it was warmed up properly. This can take a long time in the winter. If you have the MFD or a scangauge you'll see that fuel efficiency is terrible until the engine is hot.
* Keep the audio off (so you can hear the engine)
* Leave lots of space between you and the car in front (so you don't need to brake unnecessarily). I'm usually about 3 seconds behind. Some people draft to get better MPG, but this is foolish - you will write off your car sooner or later if you do that.
* Be aware of what is around you at all times (including behind), again so you don't need to brake unnecessarily
* Drive with a steady engine load (allowing RPM & speed to drift)
* Coasting in neutral with engine on - I do this as part of pulse & glide, but only over 35mph or so. Once you are at 30 or below there is no advantage.
* Coasting in gear (when you need to slow down gently, for example down a hill, or towards red lights)
* Drive as if your brake pads were made of platinum :) Every time you touch your brakes unnecessarily you waste fuel.
* Pulse & Glide (40-50mph range)
* High Speed Pulse & Glide (55-60 mph range). Always keep track of other traffic when using P&G, you don't want to irritate other drivers, and there is nothing more irritating than being stuck behind a P&Ging driver.
* Park in a high spot if you can (so when you start, gravity helps you get moving)
* Face-Out Parking so that you don't have to reverse when your engine is cold
* When it is raining, avoid the grooves in the road where the heavy vehicles have worn it out since water causes massive rolling resistance
* Use Shank's pony or a bike if your journey is short
* Avoid traffic jams, cold weather, passengers, rain, wind and driving in the dark. OK, you can't really avoid these, but be aware that they will kill your MPG.

The pulse & glide techniques only have a minimal effect on the MPG of the A2, but used to have a big effect on my old Passat. The difference is that the engine resistance of the A2 is already less due to the 3 cylinders, and also that the A2 is much lighter than the Passat (hence, the Passat would glide better because it had more momentum, and saved more fuel due to the idle making more of a difference).

Some means of knowing trip & instantaneous MPG is extremely useful. The MFD (DIS) was very useful on my old Passat. It allows you to keep track of the MPG for each journey and work out why it was good (or bad) ... for example, I used to be able to tell wind speed & direction from the effect on trip MPG as I drove.

Wheels & tyres: Avoid big rims with wide tyres, tall & narrow tyres give better MPG. Low rolling resistance (LRR) tyres also help.

In terms of mods, I have remapped, installed the 1.2TDI aerodynamic components, and scangauge. Be aware that these modifications will never repay their cost. Being realistic, it's purely for vanity not value for money. Cruise Control is OK MPG-wise on the flat, but turn it off for hills.


The other thing you need to consider is your journey - if you ever do short trips (a mile to the shops or whatever), this will really knock down your tank average. Walk or cycle instead. The car only really starts to get efficient after the engine has fully warmed up (which can be anywhere from 3 miles to 15 miles depending on the weather).

Similarly, city driving will also really push down your MPG. Every time you stop & have to get back up to speed, you are losing fuel.

If your car is new, forget all the above. You should be concentrating on running it in properly (if you always baby it while it is running in, then you will not get a good seal on the piston rings - give it a workout throughout the rev range once in a while, once it is fully up to temperature).

If you have a car with a Diesel Particulate Filter (DPF, > 2005 or so), you also have to sometimes drive it hard enough & long enough to regenerate the DPF, at least once per tank but twice is better. This is extremely important for city drivers, or drivers who only usually do short distances. Otherwise it will clag up quickly & cost you a great deal if you are in the UK or Europe. US drivers usually have it covered under manufacturer warranty so have less to worry about.
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
That’s is very informative Mike

Many thanks for that.

Couple of questions What is Pulse and Gliding a bit more detail on that please.
...
Basically it is a technique to reduce engine resistance briefly.

Pick your target speed range (for example, 40 to 50)
Pulse - accellerate up to 50
Glide - First check behind you, if it is clear, drop the car into neutral, and coast (with the engine still running) until your speed has dropped down to 40.
Repeat.

It doesn't work up long hills, into a strong headwind, high speeds (70 or over) or low speeds (under 30), but it works nicely downhill or with a tailwind. The perfect scenario is when you have a series of very small hills / undulations - power up the hill, and glide down the other side. It does work on the flat, but that takes more effort.

It is also not recommended if you have passengers, or vehicles following behind, because they will become irate quite quickly. The point of this is to reduce the average RPM (by means of being in idle for a period), and hence reduce the energy lost by friction within the engine.

Take a look at Vekke's videos (sticky post at the top of this forum), he demonstrates P&G although accellerates harder than I do (he likes 100% throttle, I prefer about 50%). I don't know which is better, these cars seem to work well either way. Theoretically about 75%-90% should work best according to the BSFC chart, but it can be hard to interpret the chart in terms of real driving conditions. He also explains many of the other driving tips well.

Can we have 44/46 PSI without affecting the tyre?...
Regarding the PSI, pump it up to your target pressure, then hold a ruler or other straight edge against the tyre contact surface. If it has bowed out, then you have to run it nearer the standard pressure. However, if it is still as flat as it was before the pressure was increased, then the tyre is good for that pressure. You'll feel much more road contact, and it should be more stable around corners, but it will give you a harsher & noisier ride (the recommended pressure is a compromise between different factors such as comfort, noise, mpg, cornering, & stopping distance. We are sacrificing some of the comfort for MPG).

I like to use Michellin Energy Saver tyres, they hold their shape well, last a long time, and roll well. But I think they are summer tyres not all-weather tyres. If you change your tyres for economy reasons alone, it only makes financial sense once your originals have worn out.
 
Last edited:

allana13

Active member
Joined
Jan 27, 2011
Location
England
TDI
VW Golf
Thanks very much for the Info Mike.

Guess its best to have 2 sets of tyres then, Winters & summers.:D
 

whitevanman

Veteran Member
Joined
Jun 25, 2011
Location
soham
TDI
passat 110 afn
I'm at a proper computer now :) This is an adapted version of something I posted on a different forum:


Note that since the weather is now subzero, the good tanks from summer are unlikely to be repeated until next may or so when the temperatures recover.

Here's the full list of techniques I use - the really important ones are in bold.

* The single most important thing is to keep your motorway cruising speed down to reduce aero drag. I usually stick to 60mph (often I am pulse&gliding between 55 and 60 where traffic, terrain & wind direction permits).
* Make sure the car is in good condition (the correct oil, clean filters, brakes not binding, etc).
* Tyres @ high pressure - I use 44/46 psi, but keep an eye on the centre wear since cheapo tyres will bulge & wear unevenly if at this pressure. Good tyres can handle the pressure fine. The tyres should never be allowed to drop below their proper pressure.
* Climate control & heater off unless absolutely essential (e.g., if it is near freezing you should have the heater on). But turn on the climate control briefly once per tank, after the engine has fully warmed up. This keeps the seals good.
* Keep windows shut above 35mph (not really relevant at the moment since they wouldn't be open in the first place!!!)
* Keep RPM low (but only when engine load is also low). When I'm going at a steady 30 on the flat I'm in 5th at around 1000 rpm. If you need to slow down / speed up / go up an incline you will need to drop a gear or two otherwise you will be overloading ('lugging') the engine. As stated elsewhere you will also need to thrash the car sometimes in order to clean out the coke. Also be aware that low-rpm/high-load will stress your clutch & transmission, so don't forget to change down using the throttle.
* Be aware of wind speed & direction and change your cruising speed appropriately (it affects aero drag). You can go faster with a tailwind but drop your cruising speed if there is a headwind.
* Keep an eye on engine temperature, be very gentle until it was warmed up properly. This can take a long time in the winter. If you have the MFD or a scangauge you'll see that fuel efficiency is terrible until the engine is hot.
* Keep the audio off (so you can hear the engine)
* Leave lots of space between you and the car in front (so you don't need to brake unnecessarily). I'm usually about 3 seconds behind. Some people draft to get better MPG, but this is foolish - you will write off your car sooner or later if you do that.
* Be aware of what is around you at all times (including behind), again so you don't need to brake unnecessarily
* Drive with a steady engine load (allowing RPM & speed to drift)
* Coasting in neutral with engine on - I do this as part of pulse & glide, but only over 35mph or so. Once you are at 30 or below there is no advantage.
* Coasting in gear (when you need to slow down gently, for example down a hill, or towards red lights)
* Drive as if your brake pads were made of platinum :) Every time you touch your brakes unnecessarily you waste fuel.
* Pulse & Glide (40-50mph range)
* High Speed Pulse & Glide (55-60 mph range). Always keep track of other traffic when using P&G, you don't want to irritate other drivers, and there is nothing more irritating than being stuck behind a P&Ging driver.
* Park in a high spot if you can (so when you start, gravity helps you get moving)
* Face-Out Parking so that you don't have to reverse when your engine is cold
* When it is raining, avoid the grooves in the road where the heavy vehicles have worn it out since water causes massive rolling resistance
* Use Shank's pony or a bike if your journey is short
* Avoid traffic jams, cold weather, passengers, rain, wind and driving in the dark. OK, you can't really avoid these, but be aware that they will kill your MPG.

The pulse & glide techniques only have a minimal effect on the MPG of the A2, but used to have a big effect on my old Passat. The difference is that the engine resistance of the A2 is already less due to the 3 cylinders, and also that the A2 is much lighter than the Passat (hence, the Passat would glide better because it had more momentum, and saved more fuel due to the idle making more of a difference).

Some means of knowing trip & instantaneous MPG is extremely useful. The MFD (DIS) was very useful on my old Passat. It allows you to keep track of the MPG for each journey and work out why it was good (or bad) ... for example, I used to be able to tell wind speed & direction from the effect on trip MPG as I drove.

Wheels & tyres: Avoid big rims with wide tyres, tall & narrow tyres give better MPG. Low rolling resistance (LRR) tyres also help.

In terms of mods, I have remapped, installed the 1.2TDI aerodynamic components, and scangauge. Be aware that these modifications will never repay their cost. Being realistic, it's purely for vanity not value for money. Cruise Control is OK MPG-wise on the flat, but turn it off for hills.


The other thing you need to consider is your journey - if you ever do short trips (a mile to the shops or whatever), this will really knock down your tank average. Walk or cycle instead. The car only really starts to get efficient after the engine has fully warmed up (which can be anywhere from 3 miles to 15 miles depending on the weather).

Similarly, city driving will also really push down your MPG. Every time you stop & have to get back up to speed, you are losing fuel.

If your car is new, forget all the above. You should be concentrating on running it in properly (if you always baby it while it is running in, then you will not get a good seal on the piston rings - give it a workout throughout the rev range once in a while, once it is fully up to temperature).

If you have a car with a Diesel Particulate Filter (DPF, > 2005 or so), you also have to sometimes drive it hard enough & long enough to regenerate the DPF, at least once per tank but twice is better. This is extremely important for city drivers, or drivers who only usually do short distances. Otherwise it will clag up quickly & cost you a great deal if you are in the UK or Europe. US drivers usually have it covered under manufacturer warranty so have less to worry about.
Sorry but Ive always been taught that a car idleing uses more fuel than a car under load? And If i was to give the car a good thrashing to put it in second gear would that be bad for it (considering ultra high mileage)
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
Sorry but I've always been taught that a car idleing uses more fuel than a car under load?
I'm not sure what part of my post you're referring to here. A stationary car will have zero mpg when idling of course (since it is not going anywhere).

I can't think of a case where a moving car in neutral & idle would be using more fuel at that moment in time than a car which is under a significant positive load at the same speed (i.e., accelerating). I'm probably misunderstanding your question.

Petrol vehicles have a very inefficient idle, but it's much more efficient on a diesel (one of the main reasons why real-world MPG is much better on diesels than petrols).

If you're referring to the neutral vs. underrun (negative load) debate, then the answer is that it depends on the circumstances - you need to use the right technique at the right time.

If you are referring to the BSFC chart (efficiency varying by load & by rpm), then you need to interpret the chart in terms of the overall dynamic picture, not just the instantaneous bsfc.

And If i was to give the car a good thrashing to put it in second gear would that be bad for it (considering ultra high mileage)
It's fine as long as a) you keep it under the red line, and b) the engine has fully warmed up to operating temperature. If you thrash it while the engine is cold that is very bad.


PS it may be a good idea to shorten the quoted part of your post since my original post was rather long & it takes up a lot of space. If you cut it down so that only the relevant parts of my post are shown, it will make things easier to read & understand.
 
Last edited:

allana13

Active member
Joined
Jan 27, 2011
Location
England
TDI
VW Golf
Mike i have followed what you have suggested and have achieved nearly 67mpg at 1 stage. I also did manage to get 60mpg on a average

Thanks:D
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
That's great :)
 

Forza91

Veteran Member
Joined
Dec 23, 2011
Location
San Diego, CA
TDI
2003 Jetta GL TDI, 2004 Golf GLS TDI
I don't really want to make driving any more scientific than it needs to be, for the most part I'm in the drive-it-like-you-stole-it camp, but what would be considered "thrashing" the car in terms of RPMs -especially when the car is warming up? I hear people say to ease into each gear but what does that mean? When it's warming up, I typically shift a little above 2000 just because I like to hear the turbo *whoosh*, but is that a no-no? On the other hand shifting too soon (around 1400rpm or so), at least for me, causes the engine to lug for a bit. Ultimately which is worse for the engine, the "thrashing" or the lugging? I got a TDI over a hybrid because I can actually drive the damn car and still get pretty great fuel economy, but I don't want to do so in a way thats going to prematurely run it into the ground.

Also how does P&G affect the lifespan of the components?
 
Last edited:

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis (where it's safe)
TDI
There are just too many to list....
I try and keep the RPMs over 2500 during warmup. That keeps the afterglow OFF. The plugs cycle on and off at 2500 RPM, or in the case of the 2002+ cars, the control unit duty cycles them up at 2500 RPM. In either case, that constant on/off of the plugs is what shortens their life. And of course never let it sit and idle after a cold start.

I'm lucky, because I have my car covered in the morning, so no scraping ice or anything, it is backed in its spot. I literally start up, drive off, 1-2-3-4 and I am doing 60. Hold 60 in 4th (above 2500 RPM) for that first couple miles on two-lane black top until I merge on to the interstate... then hammer down and into 5th and 80+ for 40 minutes. Probably why my cars last so long. They get up to temp very quickly, and are mostly hwy miles.
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
...
Also how does P&G affect the lifespan of the components?
It's very hard (brutal) on the clutch & transmission if you are doing 'engine-off' coasting. However that's not a good idea anyway due to the loss of vacuum causing the brake & steering to become hard.

'Engine-on' coasting is more benign, but does involve many more gear changes than otherwise, so a degree of extra wear is to be expected.

I personally would keep both load & rpm low until the engine has heated up properly. The engine oil only becomes fluid when the engine is hot.

Once the engine is hot, then you can push it up to the red line as often as you want (but for the purposes of de-coking you only need to do it once a tank or two). Note that revving with no load isn't particularly useful, you need to be putting the engine under load (i.e., up a hill in 4th).
 
Last edited:

an60an

Veteran Member
Joined
Aug 1, 2009
Location
SLC/Utah
TDI
2002 Golf TDI 5 speed 2003 Golf TDI 5 speed
.......
Once the engine is hot, then you can push it up to the red line as often as you want (but for the purposes of de-coking you only need to do it once a tank or two). Note that revving with no load isn't particularly useful, you need to be putting the engine under load (i.e., up a hill in 4th).
Or you could just drive at 50, drop down to 3rd and go for it:D all the way to 75/80, the car blow all the crap out :)
 

lojosh

Well-known member
Joined
Jan 3, 2012
Location
Kansas
TDI
2001 Beeetle TDI
fuel economy

I was reading the post on fuel economy and it mention something about a Italian tune up.Do you keep doing this until the black smoke quits or just lessons.
 

vlad0401

Veteran Member
Joined
Aug 27, 2011
Location
Clinton, NY
TDI
2003 Golf GL
I try and keep the RPMs over 2500 during warmup. That keeps the afterglow OFF. The plugs cycle on and off at 2500 RPM, or in the case of the 2002+ cars, the control unit duty cycles them up at 2500 RPM. In either case, that constant on/off of the plugs is what shortens their life. And of course never let it sit and idle after a cold start.

I'm lucky, because I have my car covered in the morning, so no scraping ice or anything, it is backed in its spot. I literally start up, drive off, 1-2-3-4 and I am doing 60. Hold 60 in 4th (above 2500 RPM) for that first couple miles on two-lane black top until I merge on to the interstate... then hammer down and into 5th and 80+ for 40 minutes. Probably why my cars last so long. They get up to temp very quickly, and are mostly hwy miles.
why is it bad to let a car sit after a cold start? i assume that means under 32 degrees Fahrenheit. i let me car sit for 5-15 mins before i go to school every monday-friday temp is usually below 32 every morning for the past 2 months
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
why is it bad to let a car sit after a cold start? i assume that means under 32 degrees Fahrenheit. i let me car sit for 5-15 mins before i go to school every monday-friday temp is usually below 32 every morning for the past 2 months
a) Idling does not really help a diesel engine to warm up. You need to be driving around to use enough fuel to warm up the engine.

b) While the engine is running cold, the oil is not very fluid, & hence you get extra engine wear.

c) What is to stop someone walking up to your car & just taking it? If this happens in the UK, the insurance company will just laugh at you & refuse to pay out.

d) It's illegal in some areas (I have no idea whether that applies to your area).


Why not invest in a block heater, and pre-heat the coolant before starting?
 
Last edited:

allana13

Active member
Joined
Jan 27, 2011
Location
England
TDI
VW Golf
Hi Mike,

The Block heater is something I haven’t heard of before. What is it, where does it fit, how much does it cost and how does it help in increasing fuel efficiency.

Many thanks for your help in advance. Much appreciated as I have increased my fuel economy using the tips you mentioned.:D





a) Idling does not really help a diesel engine to warm up. You need to be driving around to use enough fuel to warm up the engine.
b) While the engine is running cold, the oil is not very fluid, & hence you get extra engine wear.
c) What is to stop someone walking up to your car & just taking it? If this happens in the UK, the insurance company will just laugh at you & refuse to pay out.
d) It's illegal in some areas (I have no idea whether that applies to your area).
Why not invest in a block heater, and pre-heat the coolant before starting?
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
Well, they're not really needed here in the UK (not cold enough), but if I understand correctly, it's basically a glow-plug which screws into the sump. You plug it into the mains on a timer so that it starts to heat up 2 hours before you are due to start in the morning.

They will help the fuel efficiency, because the engine is less efficient when cold, and the block heater pre-heats the engine.


This looks like a useful thread about them:
http://forums.tdiclub.com/showthread.php?t=315072
 
Last edited:

Padrino

Veteran Member
Joined
Jun 16, 2009
Location
Western US
TDI
2002 / Golf 1.9 TDI 5-speed
Well, they're not really needed here in the UK (not cold enough), but if I understand correctly, it's basically a glow-plug which screws into the sump. You plug it into the mains on a timer so that it starts to heat up 2 hours before you are due to start in the morning.

They will help the fuel efficiency, because the engine is less efficient when cold, and the block heater pre-heats the engine.


This looks like a useful thread about them:
http://forums.tdiclub.com/showthread.php?t=315072
As usual Mike boy is better than search function.
How you manage to keep a tap on everything here Mike?
Your posting are always very informative but I just don't have that much time to go and search for every bid of info, looks like you have some "secret" system :D
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
All I did was search for 'block heater' ... :)
 

vdubtdi11

Well-known member
Joined
Feb 8, 2012
Location
NoVA
TDI
2011 golf TDI
My TDI is 2011 with just over 5k on it and I usually get about 47 on the highway at about 65. The car LOVES the 40-50 mph range where it can easily achieve mid 60's+.(too bad there is nowhere that one can drive for hours at 45mph..) In the beginning, I was mainly driving on the highway. Its just recently that I have started driving in town with it more where I usually drive my truck and I find that if I drive carefully and allow my torque to do its job to get me up to speed, my trips have resulted in the low to mid 40s! One trip, (when there was no traffic) I got 47.6 for an 11 mile suburban trip! Once the car gets up over 70 mph, the fuel economy can drop as low as 39!
 
Last edited:

vdubtdi11

Well-known member
Joined
Feb 8, 2012
Location
NoVA
TDI
2011 golf TDI
BTW, is it possible for my new car to be making black smoke when I floor it? Has there been time for soot build up? My friend said he saw black smoke when I did that but I didn't see any. I do baby the car 99% of the time but I still feel like after then 3000 highway miles, that that shouldn't be a problem. Also, when Oilhammer said to drive with spirit to clear out the engine and help the turbo and intake, would normal 75mph on the highway be sufficient?
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
...drive with spirit to clear out the engine and help the turbo and intake, would normal 75mph on the highway be sufficient?
It does sound like you are coked up.

Drop down to 4th and do the 75mph for a minute or two (preferably when going uphill). Do this once per tank or two and that should be enough.
 

kay.DIESLpwr

Member
Joined
Mar 28, 2012
Location
California
TDI
2012 Jetta, DSG
a) Idling does not really help a diesel engine to warm up. You need to be driving around to use enough fuel to warm up the engine.

b) While the engine is running cold, the oil is not very fluid, & hence you get extra engine wear.

c) What is to stop someone walking up to your car & just taking it? If this happens in the UK, the insurance company will just laugh at you & refuse to pay out.

d) It's illegal in some areas (I have no idea whether that applies to your area).


Why not invest in a block heater, and pre-heat the coolant before starting?
hey Mike, im new here and i just got accptd today actually and what you said in A) is actually let the car run after a cold start?
and about using neutral while in gear(for automatic), isnt that bad for your engine? and i also read that coasting in neutral eats gas than coasting in gear.
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
hey Mike, im new here and i just got accptd today actually and what you said in A) is actually let the car run after a cold start?
and about using neutral while in gear(for automatic), isnt that bad for your engine? and i also read that coasting in neutral eats gas than coasting in gear.
Answering via phone so please excuse terse reply.

Do NOT idle to warm up. Get in the car and drive without waiting for it to warm up.

When I refer to neutral it is always in the context of a manual gearbox. I have never owned a car with a slushbox and know little about them because few people use them in this country.

Neutral vs. in gear ... This is a complex situation, and both techniques should be used in the right circumstance. If you want to slow down via engine breaking then in gear is best since that uses zero fuel. However if you want to roll without wasting kinetic energy on the level or downhill then neutral is best over 35mph or so.
 
Last edited:

kay.DIESLpwr

Member
Joined
Mar 28, 2012
Location
California
TDI
2012 Jetta, DSG
Answering via phone so please excuse terse reply.

Do NOT idle to warm up. Get in the car and drive without waiting for it to warm up.

When I refer to neutral it is always in the context of a manual gearbox. I have never owned a car with a slushbox and know little about them because few people use them in this country.

Neutral vs. in gear ... This is a complex situation, and both techniques should be used in the right circumstance. If you want to slow down via engine breaking then in gear is best since that uses zero fuel. However if you want to roll without wasting kinetic energy on the level or downhill then neutral is best over 35mph or so.
oh so just run the car right away after cold start then? but when i or my dad drive it, we hear this weird sound in the engine. is that ok? i mean its been like this since we got it. so whenever it happens, we just stop on the curb and wait 1-3 mins then runs fine again.

hmm, well i use to always use neutral when im going down a hill at 40+mph and i read a post somewhere and stopped it right away and in this forums, i kept reading that neutral is fine(i know they are talking about manual trans) but im kind of confused now though..:(
 
Last edited:

allana13

Active member
Joined
Jan 27, 2011
Location
England
TDI
VW Golf
Achived 70.4mpg with BP ultimate diesel cruising at 60MPH for a distance of 45miles on the motorway

Well chuffed.
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
Achived 70.4mpg with BP ultimate diesel cruising at 60MPH for a distance of 45miles on the motorway

Well chuffed.
Good work, congratulations on that. The next target is to see if you can beat your 'high score' on the full tank :)


Your 70mpg(imp) / 60 mph fits the forum's '120 rule' perfectly (after converting to us gal).
 

allana13

Active member
Joined
Jan 27, 2011
Location
England
TDI
VW Golf
Thanks Mike,

I am hoping with a service that should improve the MPG.

But yes the key to high MPG i felt was driving at 60mph

The moment I went to 70mph it drops down.
 
Top