What does it take to get 60+ MPG?

[snakeye]

I've been coasting a lot in neutral (downhill, to a stop), and rolling at around 55mph on the highway, and so far my best fill up has been 56mpg. I'm looking to improve my mileage even more; any advice?

Btw I didn't know it was so easy to get such good mileage out of my car. Just a few months ago I was reading of people getting over 1300km on a tank and though it was bs. Now I'm getting 1400 and up.

 

[JSWTDI09]

If you haven't read it this might help: http://forums.tdiclub.com/showthread.php?t=200694

What does it take to get 60mpg?

It takes the right weather, the right fuel, the right car, a carefully chosen route, patience, and most of all practice. Pretend you have very expensive carpet in your car and somebody taped a rotten egg to the bottom of your right shoe. Be very gentile on the go pedal, you do not want to break that egg. Keep power demand and rpms as low as possible.

Perhaps, the real question is why do want to average 60mpg? If this is your idea of fun, then by all means go for it. However in my opinion, getting that last 3 or 4 mpgs is a lot of work for very little gain. Everybody is different, the choice is yours.

Have Fun!

Don

 

[UFO]

Downhill coasting in neutral uses more fuel than leaving it in the right gear.

 

[Lug_Nut]

However in my opinion, getting that last 3 or 4 mpgs is a lot of work for very little gain.

But knowing HOW you can get that 3 or 4 (or 20) additional miles per gallon, over extended distances, in your car can be a big advantage.
"Next diesel: 85 miles" no problem. But then that station is closed for repairs and the next one is another 60 miles further. Now what?

 

[Joe_Meehan]

Downhill coasting in neutral uses more fuel than leaving it in the right gear.

Let me add. Your car uses fuel whenever it is running EXCEPT when the car is in gear and the engine is being turned over faster than idle speed. Your TDI will turn off all fuel which means you are getting infinite mileage under those conditions. If you leave it in gear as long as the car is turning the engine over at or above the idle speed you are doing better than being in neutral where the car will burn gas to keep the engine running.

OK that is really the simple version. You need to factor in a few more things like speed, wind road conditions up hill vs down hill etc…… If you pick just the right combinations you win, while doing a lot more work than doing almost as good with a lot less effort.

You get to choose how much it is worth to you.

Note: Your TDI will do very well no matter what you do. I don't work that hard at it myself, and I get better mileage than almost any other car on the road, but if you want to squeeze that last 0.025 mpg, Go for it.

 

[BioBob]

Coasting in Neutral

Before you condemn coasting because the engine is running, you need to try Pulse and Glide on a route you take often.

The route I tried is between Wytheville VA. and Charleston WV.

I had driven it several times with the cruise set. Very repeatable, always in the 62 MPG range (my car likes hills rather than flat land).

When I tried P&G the first time I got 74 MPG. Thinking I may have had a tailwind, I tried it again and was astounded with 77 MPG.

WHY does it work better? At the bottom of a hill with the cruise on, you will be at the same speed as when you began the descent. With P&G, you will be going much faster (depending on the hill) and the glide (the distance gained with the coast) is where you make the gains.

I now P&G in town! When the scan gauge shows me 90 MPG going down hill, I shift to neutral. This is the point at which I begin to gain speed on the downhill run. When you can gain speed, then you gain on the Glide.

There are many hills where I do both. When the glide speed gets above 75, I then re-engage the transmission and shut off the injectors.

Try it -- You'll like it!

 

[BioBob]

60 mpg

Hey Snakeye :

If you are serious about getting in the 60 range, get a Scangauge to teach your right foot how to behave.

It will also help you to evaluate the different techniques you are experimenting with.

I trust you have already pumped up your tires, checked your alignment, and are on LRR tires. If just leaning on your car at rest on a flat surface will move it, you're half way there already, the next half will be up to your right foot, and your gearshift.

Once you develop your technique it will become automatic. Your passengers will wonder what in H*** you are doing, just assure them that they are in good hands, and gliding along at 60 MPG. How GREEN is that!

I'm now working on an 80 MPG car and should be there in the spring.

 

[snakeye]

Perhaps, the real question is why do want to average 60mpg? If this is your idea of fun, then by all means go for it. However in my opinion, getting that last 3 or 4 mpgs is a lot of work for very little gain. Everybody is different, the choice is yours.

Bragging rights, and also want to see how far I can go on a tank.

Let me add. Your car uses fuel whenever it is running EXCEPT when the car is in gear and the engine is being turned over faster than idle speed. Your TDI will turn off all fuel which means you are getting infinite mileage under those conditions. If you leave it in gear as long as the car is turning the engine over at or above the idle speed you are doing better than being in neutral where the car will burn gas to keep the engine running.

OK that is really the simple version. You need to factor in a few more things like speed, wind road conditions up hill vs down hill etc…… If you pick just the right combinations you win, while doing a lot more work than doing almost as good with a lot less effort.

You get to choose how much it is worth to you.

Note: Your TDI will do very well no matter what you do. I don't work that hard at it myself, and I get better mileage than almost any other car on the road, but if you want to squeeze that last 0.025 mpg, Go for it.

Right. I'm perfectly aware of the fact that keeping the car in gear uses zero fuel, but most of my downhill coasting is done on not very steep inclinations, and therefore the engine compression slows my car down too much, whereas coasting in gear allows me to maintain my speed until I reach the bottom. Coasting in neutral before a stop also allows me to travel many times the distance as if I was in gear. I do coast in gear sometimes, but it really depends on the circumstances.

BioBob it's pretty much what I do, I P&G somewhat, but only on hills. I don't bother on straight roads.

I think I'll invest in a scangauge once I have the money.

 

[Joe_Meehan]

It should be considered that all the mileage computers are measuring fuel usage indirectly. In other words they do some estimating of fuel usage. I am amazed at how accurate they are, but they are not 100%

How accurate depends on a number of factors. Hills, P&G and other factors may cause errors.

While I have no accurate data and don't plan on doing the necessary testing to get solid numbers, I suspect that P&G, different terrain, weather etc. can cause false read outs, especially of the current MPG numbers.

I just can't get that old statistician in me from questioning data that may be subject to unexpected, untested errors.

 

[Lug_Nut]

No P&G, (forbidden by the rules), no EOC, (forbidden), no drafting, no modifications (stock class rules), maximum lap time (minimum speed limit) and minimum lap time (no speeding), public streets,
250 miles distance, 82+ MPG on B100, 1996 B4 with 250k+ miles (2003 Tour de Sol)
500 miles distance, 78+ MPG on B100, 1996 B4V with 200k+ miles (2005 Tour de Sol)
125 miles distance, 68+ MPG on B100, 2005 B5.5V with 150k+ miles (21st Century Automotive Challenge).

I have P&G'd, It works quite well in my 1969 Sonett (44+ mpg, Vintage class, Adirondac Motor Enthusiasts Club's Fall Foliage Tour), compared to an estimated 25 MPG when the car was new.
P&G is less effective on the TDI than 'constant load' operation.

 

[snakeye]

No P&G, (forbidden by the rules), no EOC, (forbidden), no drafting, no modifications (stock class rules), maximum lap time (minimum speed limit) and minimum lap time (no speeding), public streets,
250 miles distance, 82+ MPG on B100, 1996 B4 with 250k+ miles (2003 Tour de Sol)
500 miles distance, 78+ MPG on B100, 1996 B4V with 200k+ miles (2005 Tour de Sol)
125 miles distance, 68+ MPG on B100, 2005 B5.5V with 150k+ miles (21st Century Automotive Challenge).

I have P&G'd, It works quite well in my 1969 Sonett (44+ mpg, Vintage class, Adirondac Motor Enthusiasts Club's Fall Foliage Tour), compared to an estimated 25 MPG when the car was new.
P&G is less effective on the TDI than 'constant load' operation.

So... what's the secret? Btw what's EOC?

 

[TDIMeister]

Lug_Nut doth knoweth what he says.

 

[shizzler]

Agreed, except for the whole "P & G doesn't work" thing. Haha Why would the concept work on one of your cars but not another? I'm willing to bet the BSFC maps for each engine share similar trends - BSFC decreases with load. I.E. similar to just about every engine out there.
Seriously though, there's loads of evidence / proof / fuel logs.... but whatever.

Everyone is still talking only about driving style. I just don't get it.
Vehicle mods are the easy (but ugly) way to get 60 mpg. Driving style is the difficult way.

I aero-modded my car - just moderately - and I get 55-56 mpg (repeatedly) at 75-80 mph, no attention to driving style at all. I should probably summon a tank full of patience, slow down to 60 mph, and pull off some 60+ mpg #s huh?

Oh and EOC is engine off coasting. Can be very helpful if you live in a hilly (but not mountainous!) area. Pretty dangerous stuff, generally not worth it.

 

[snakeye]

lol yeah I'll keep my engine on. I'm not ready to risk turning the key a bit too far and ending up 6 feet underground a few days later. What was it, 0.2 liters per hour when your engine is idling? I can live with that.

shizzler I can probably gain a couple of MPG just be restoring my car's body to stock. Right now the bumper is anything but smooth, and I'm missing the skid plate, which probably lowers the drag under the car. I'm looking more for driving techniques.

 

[Timpackman]

so going down hill, in gear, above idle, burns no fuel?

 

[UFO]

I've never tested P&G myself, but I will not write it off out-of-hand. I am amazed how my highway mileage increases when I drive through the mountains, high load up the hills, zero fuel use back down. A round trip from Denver to Glenwood Springs, 50mph average (winter conditions) netted me 55mpg, where a round trip from Denver to Crestone, less hilly, same mph average got 50mpg. More hills seem to improve the mileage lending credence to the pulse and glide technique.

 

[Turbospool]

I'm certainly no pro like some on here, ..... but if getting over 60 mpg is possible for a hill billy like me, tank after tank, you can do it too. That's the only true test to this 60 plus thing, 2-3 tanks back to back. The following is my observation. Low rolling resistance tires pumped to 45psi, warm summer air (I can't tell you why, but it definitely makes a difference), fresh fuel ( where there is high flow diesel sales), moderately hilly terrain and P&G only on "speed gaining downhills", never shut her off, keep my speed between 45 - 60 on a 55mph limit commute. Scanguage taught foot (wouldn't need it anymore), want mine? Can't have it though LOL, sprint 520's with RC 2 have givin me torque to boot, so I have fun and fair mpg #'s ......while not the record with these guys on this forum. You will love it , I sure do.

 

[Rattler05.5]

so going down hill, in gear, above idle, burns no fuel?

Yeppers, ZERO. With a manual, if you use first gear to decelerate you can hear the injectors/engine start firing again at ~1200RPM

 

[hyperhyper]

No fuel used when coasting in gear

Timpackman
The scan gauge will tell the story as it will show 9999MPG when rpm is above idle. Try this (one time) when traffic allows: set the cruise in 5th gear at about 40MPH and take your foot off the accelerator. When your engine reaches idling speed, it will surge as it goes from 9999MPG to ~70MPG. This is not particularly good for the engine, so don't make a practice of it.

 

[thebigarniedog]

Hey Snakeye :

If you are serious about getting in the 60 range, get a Scangauge to teach your right foot how to behave.....

This is the best advice in this thread. One can also gear their vehicle for fuel economy (i.e. using fuel max tires on 15 inch rims (for the mk4), dumping un-necessary weight (i.e. that 200 pound girlfriend Bob rides around with), combined with coasting in gear then neutral coasting and not wasting fuel by downshifting).

Bragging rights .....

and this is why I ignore all claims of mpg substantially outside of the epa rated economy (too many liers) .....

 

[snakeye]

This is the best advice in this thread. One can also gear their vehicle for fuel economy (i.e. using fuel max tires on 15 inch rims (for the mk4), dumping un-necessary weight (i.e. that 200 pound girlfriend Bob rides around with), combined with coasting in gear then neutral coasting and not wasting fuel by downshifting).



and this is why I ignore all claims of mpg substantially outside of the epa rated economy (too many liers) .....

Well I found it pretty easy to get 56 MPG, but I just came back from a road trip today and used a friend's GPS which told me I was going about 4-5 km/h slower than it was indicated on the speedometer. If that's the case, the odometer might be off as well by a little, and I might not be getting the most accurate MPG, and probably the same goes for a lot of people here.

Still if I can get near 50 MPG with no mods, quite a bit of clunking noise from the wheels, a busted fender, paint chipped bumper, crappy & dirty paint, not overly inflated tires and no skid plate, then I very much believe that someone can get 60+ MPG easily with a few mods and the right kind of driving.

Btw just because someone wants to brag about his mileage doesn't mean he's lying. Do you believe that someone can get 70 MPG on a TDI? If you do then how would you determine who's saying the truth and who's lying?

 

[fflis]

so going down hill, in gear, above idle, burns no fuel?

Hmm it sounds like that's what was said above. I always wondered if coasting at idle was better than leaving in gear. I'll have to try this. Lately I've been quite the lead foot, pretty much racing around town at 36mpg. Yikes I know. I recently put 18" rc wheels on too and added roof racks.

Any idea what kind of mileage loss you experience with big wheels?

 

[thebigarniedog]

Well I found it pretty easy to get 56 MPG, but I just came back from a road trip today and used a friend's GPS which told me I was going about 4-5 km/h slower than it was indicated on the speedometer. If that's the case, the odometer might be off as well by a little, and I might not be getting the most accurate MPG, and probably the same goes for a lot of people here.

Still if I can get near 50 MPG with no mods, quite a bit of clunking noise from the wheels, a busted fender, paint chipped bumper, crappy & dirty paint, not overly inflated tires and no skid plate, then I very much believe that someone can get 60+ MPG easily with a few mods and the right kind of driving.

Btw just because someone wants to brag about his mileage doesn't mean he's lying. Do you believe that someone can get 70 MPG on a TDI? If you do then how would you determine who's saying the truth and who's lying?

You should check your odo with your GPS. Lots of threads discuss how the odo usually is dead on all things being equal, yet the mph/kph is deliberately skewed. MFA mpg readings tend to always be high; pad and paper with good numbers is the accepted measurement of mpgs.

I use the test for truthfulness that I employ in my day to day life. It is a proprietary system that is arbitrary, capricious and completely unreasonable .

 

[XaqNautilus]

But knowing HOW you can get that 3 or 4 (or 20) additional miles per gallon, over extended distances, in your car can be a big advantage.
"Next diesel: 85 miles" no problem. But then that station is closed for repairs and the next one is another 60 miles further. Now what?

Hahaha. Been there. Drafting a big rig for the win! Easy to get over 60 mpg if you draft.

Disclaimer: I do NOT recommend drafting.

 

[85_305]

I haven't read thru the thread, but here is something to consider. Of all the 5spds I've ever owned, including several diesel trucks and my tdi, the motor and the mileage both like the rpm's being drawn out before shifting. Short shifting KILLS mileage, not saves it. So instead of lugging the motor, try shifting at a MINIMUM of 2500rpms. Often times I go up to 3,000 or even 3500rpms on hills. You'll burn less fuel keeping it in gear spinning higher rpms because the motor will cut fuel to make it more efficient, whereas lugging it starts dumping fuel to keep the motor alive and up to meeting your required demands.

Also, invest in a boost gauge. When I'm putting around down, I dont let the car aquire more than 5-7psi of boost. I average 51-52mpg around town, and over 60 on the highway driving like this. Diesels are VERY forgiving of being romped on; thats how a diesel is designed to run. So every few days, romp it, clean it out, stretch those injectors and turbo, and then continue babying it. This is what I do, and I NEVER get below 51mpg driving in the city.

Oh and that brings me to another point. Diesels LOVE to be modded. The more efficiently a diesel can run and drive, the more efficient it will be in the fuel tank. Being able to produce more torque using less fuel means you touch that accelerator pedal less, meaning less fuel is introduced into the combustion chamber. So with that being said, all said mods in my signtare do a damn good job at keeping mileage high.

 

[THERAT]

... best way to get 60 miles per gallon is to use the Imperial conversion factor, I've got a feeling some confusion is coming from US gallon conversions vs the Imperial conversion, or possibly a mixture of the two. For instance I have a stock 2003 Jetta TDI with 200,000 KM and consistently get between 4 and 5 litres/100k on the highway at an average speed of 100 - 110 km/hr (60-70 mph) during 1000k (670 mi) tours. This works out to be between 59 miles per gal (US)/or 70 mpg (IMP) and 47 mpg (US)/or 56 mpg (IMP). On long trips I always start off with a vented tank. My confusion comes with whether after venting my tank is full at 55 litres as stated in the manuel. On one trip I let the tank go to a little over 1200 K filled and vented it to nearly 55 litres. If the tank was empty that would have given me an actual reading of 4.5 litres per 100 k or 62 miles per gal (IMP) and 52 mpg (US). I've never run my tank to empty so I don't know whether the 55 litre capacty is true. This has held true for both winter and summer driving with both winter or summer tires. City driving is less, however, particularily in the winter.

 

[bgarfield]

Understanding carrying momentum is a HUGE part of it. The less you slow down, the more you don't use fuel to speed up.

Anytime you've used the brakes, you've wasted fuel. Obviously, you can't be too extreme with this idea on the road around other traffic, but there's no arguing that it's true.

I've been getting awesome mileage in my '09 based on this simple concept as seen on one of my trip averages below.

Brian

 

[Turbospool]

... best way to get 60 miles per gallon is to use the Imperial conversion factor, I've got a feeling some confusion is coming from US gallon conversions vs the Imperial conversion, or possibly a mixture of the two. For instance I have a stock 2003 Jetta TDI with 200,000 KM and consistently get between 4 and 5 litres/100k on the highway at an average speed of 100 - 110 km/hr (60-70 mph) during 1000k (670 mi) tours. This works out to be between 59 miles per gal (US)/or 70 mpg (IMP) and 47 mpg (US)/or 56 mpg (IMP). On long trips I always start off with a vented tank. My confusion comes with whether after venting my tank is full at 55 litres as stated in the manuel. On one trip I let the tank go to a little over 1200 K filled and vented it to nearly 55 litres. If the tank was empty that would have given me an actual reading of 4.5 litres per 100 k or 62 miles per gal (IMP) and 52 mpg (US). I've never run my tank to empty so I don't know whether the 55 litre capacty is true. This has held true for both winter and summer driving with both winter or summer tires. City driving is less, however, particularily in the winter.

This Is USA gallons .... and it can be done. I'll maybe be blowing my own horn here, so be it .... last 5 fillups all 60 mpg plus. This is summer time milage, the only time I can do it.

 

[DonL]

60 mpg

Okay, count me as one who wants the 60 mpg tank, but add I want the 900 mile tank too. My best so far is 55 mpg. I just don't have the patience for the long trip at 55 mpg, etc. I think 870 is my best tank so far.

However, I did get a solid 67 mpg or better in my 1980 Dasher diesel wagon back in about 1983. I still have my record book if I need to look it up. It was late April, going south on I-5 in California's central valley, with a terrific tailwind. I filled at the north end of the valley and again on the other side of the Grapevine. I knew my mileage was terrific, so I filled it until I could see the diesel in the neck. The calculation came out to 67 mpg, but since I had filled it fuller, it was actually higher.

I suspect under similar conditions and speed, my Jetta would do even better.

As for drafting, I do it all the time. However, I discovered, in my Dodges with the overhead display, that following a truck at safe following distance, eg three second rule, still gives a pretty good mpg increase. However, trucks don't tool down the freeway at 55 mpg, so usually you have to be going 65 or better to draft.

Also on drafting, a lot of truckers do this. They exchange the lead and you might have three or four trucks, or more, in a convey to improve mpgs. At the difference between 6 and 7 it can really add up.

I didn't do drafting back when I had the Dasher because back then I though you had to tailgate the truck and I am never willing to do that.

One other point, a conditioner that boosts Cetane helps.

 

[casanis1]

I'm averaging 56.1MPG with my best so far being 59.8MPG. not a TDI though - stock 1985 1.6 NA (w/ Giles Pump). I have found the best addition to fuel economy to be a light right foot combined with this on the back end: