Hypermiling videos to better fuel consumption

[Justin Rizzo]

Justin - there is a key difference between this thread and Drivbiwire's thread. This thread is about maximum fuel efficiency and Drivbiwire's is about engine break-in without regard to fuel efficiency.

Good point. I figured since he had items up to 60k to life of the car, the principles carried upward. I edited my question accordingly.

I still want to know if I am correct in the following concepts:

From what I have read so far I assumed it would be wise to keep the RPM between 1700-2400 when speeding up with a max of 75% on the pedal. This would not be considered harmful to the turbo as it hits the "sweet spot" with the boost (not babying it) and keeps mild RPMs for fuel economy. From my gasser experience I assumed that it would be wise to cruise in 4th when going 30mph vs 3rd (shifting down to 3rd when the time came to accelerate).

 

[VeeDubTDI]

That sounds like a pretty good average target for an ALH engine to me. Don't be afraid to go beyond that up to mid-high 3000 RPMs and 100% throttle an a semi-regular basis. While it isn't ideal for fuel economy, it will serve to keep everything clean and clear.

 

[MikeMars]

...

From what I have read so far I assumed it would be wise to keep the RPM between 1700-2400 when speeding up with a max of 75% on the pedal. This would not be considered harmful to the turbo as it hits the "sweet spot" with the boost (not babying it) and keeps mild RPMs for fuel economy. From my gasser experience I assumed that it would be wise to cruise in 4th when going 30mph vs 3rd (shifting down to 3rd when the time came to accelerate).

Yes, generally you want your RPM to be higher during acceleration than during cruising, and the torque peak (1700-ish on the ALH) is a reasonable place to start acceleration. But you will be spending much more time cruising than you do accelerating (that's why I said you need to change down before accelerating).

I also do 4th gear for 30mph cruising. It is roughly 1400rpm or so, and the engine is happy at that point provided that the engine-load is gentle. When I'm cruising on the motorway at 60mph (engine load = roughly 20 hp at that point for the A2, 25 for the Jetta) I'll be in 6th @ 1750 rpm, unless I am about to go up a hill in which case I drop down to 5th (2000 rpm, engine load probably around 40hp depending on the hill).

In your earlier post you were talking about 2000rpm rather than 1700 which is why I raised the red flag. But 1700 is fine.



There is no single perfect RPM for any situation ... fuel efficiency wants lower RPMs and high torque, your clutch/gearbox wants mid-RPMs and low torque for longevity, performance wants high RPMs... ultimately it is a trade-off between those different things which is why you are being given conflicting advice. Weirdly the ALH engines seem to actually like to be driven in a variety of different ways rather than always sticking to one driving style.

...
Italian tune? you me mean peg red line?
when I 1st got my car it was very sooty on the high RPM pulls, hard launches, brake boost launches,etc, now the back of the car is pretty clean in comparison. guessing the previous owners kept the revs low and never got on it and I was blowing out all the build up.

Yes, red-line & lots of engine load (for example, flooring it in 4th up a long hill). If you normally stick to low RPMs, you need to blow away the cobwebs every now and then. Once per 2 tanks is sufficient. Obviously you should only do this once the engine is fully up to operating temperature.

 

[Justin Rizzo]

Thank you very much Mike and VeeDub! Those are the precise answers I was looking for.

This weekend I'm putting in new oil/air/fuel filters, installing a skid shield (missing my splash guard), performing a diesel purge, and filling up with a proper cetane fuel (Chevron instead of Valero). So I'm hoping to notice significant differences.

 

[TDIMeister]

A contrarian approach:
http://www.torquenews.com/1084/how-2013-volkswagen-passat-tdi-sets-world-record-78-mpg

How was 77.99 mpg achieved?
They left VW headquarters in Hendon Virginia on June 7th and traveled 8122 miles visiting all 48 U.S. states. They arrived back on June 24th. The pair of professional drivers employed many techniques to pull off the 77.99 mpg feat. Gerdes says they “looked for impediments or topography 15 to 45 seconds ahead, rather than reacting to where they were currently driving.”
They also used downhill momentum to help crest an uphill section of highway. They pulled away very slowly from a stop light and coasted between traffic lights, and they never went over the speed limit. They also went 55 instead of the posted 75 mph limit on the Interstate. In other words, they were driving very slowly and conservatively during the over 8000 mile trip. But is this possible for you?

 

[VeeDubTDI]

Not really contrarian because Vekke recommends coasting between lights, predicting the conditions ahead and adjusting accordingly, and using downhill momentum to get you up the next hill. Traveling at 55 mph instead of 75 mph is a no-brainer, too... 75 crushes your fuel economy.

The only thing really contrary is the slow acceleration vs. quick acceleration followed by coasting.

 

[TDIMeister]

Right, it was the last part that I was referring to.

As an engine/automotive engineer, I actually don't buy the slow acceleration argument. By doing this you are operating the engine at lower load / higher BSFC and, since you are accelerating at a slower rate, you have to continue at it for a longer time before you reach a desired speed. In truth, out of over 8k miles of driving, such acceleration scenarios represent a tiny fraction of one percent, so I think it's really a wash.

I think the lesson to learn is that driving for economy represents an all-encompassing set of driving style rather than one or two tricks/actions.

Out of interest of not prematurely wearing out the clutch, I will not shift into neutral after every "pulse" cycle, but I am trying a variation of pulse-and-glide whereby I set the cruise control at the posted speed limit according to the speedo (in reality a little less because of the optimistic reading) and gradually accelerate up to 10 over the CC speed and coast in-gear the rest until I drop back to the set point (all the while strategizing in advance whether I have an up- or downhill grade ahead of me). Then repeat the process. The rationale is for the engine to operate either at high load / low BSFC for a limited time or coasting/overrun where it's injecting no fuel or idling over a longer period. Only on prolonged coasting (1 minute or more) and depending on grade will I shift to neutral.

Otherwise I agree completely with the consensus approaches.

In real-world driving situations and real-world deadlines to be at a certain place at a certain time, I won't drive consistently 20 under for the sake of the distinction to save the order of one litre fuel consumption per 100km. I will, however, plan my routes and schedules in advance better to avoid congested areas/times and train myself to plan my drive out to the horizon to avoid unnecessary braking or acceleration.

 

[PressEnter[]]

Well, it clearly works for them. I accelerate with a good bit of boost, and I'm OK with my crappy 50 mpg

 

[SD26]

I still want to know if I am correct in the following concepts:

From what I have read so far I assumed it would be wise to keep the RPM between 1700-2400 when speeding up with a max of 75% on the pedal.

Kept hearing that in my head...

Usually, I shift earlier in the RPM's.

Now the max of 75% on the pedal... I changed my Scangauge settings so that I had LOD, TPS, and MAP all together. If I used 75% on the throttle position (TPS), the engine load would often go well above 75% and even well into the 80s if not all the way to 99 (doesn't go to 100). I think one might want to do 75% load rather than 75% of pedal...

Anyone want to interject?

 

[MikeMars]

... I think one might want to do 75% load rather than 75% of pedal...

Anyone want to interject?

Well, sure, 75% load is a good point on the BSFC chart, but only some of us have a load meter (scangauge / ultragauge). Everyone else has no choice but to guess.

 

[Vekke]

Side comment. Its not necessary to put the car in neutral if you have very gentle throttle pedal feel. apply just that much gas that your instant fuel consumption sets to to same level as idle fuel consumption in neutral on same speed. Its not totally the same thing as cruising in neutral but roughly the effect is the same. Its safer to be little bit over the idle fuel consumption so you are not "engine braking" the speed off.

I mean engine would need that same amount of fuel anyway. I think it works like that but havent made very scientific analysis yet on this technigue.

 

[Vekke]

To Justin. It takes time to learn how and what technigues work best for your car and where you ride, roads and climate tires etc all effect fuel consumption.

Gently throttle on accelerations is one way. That makes it possible to anticipate the traffic better as situations dont come to your face specially in city or rushhour driving that works

but if roads are empty rapid accelerations to posted speed limit is more fuel efficient with proper shift points.

cruise vs p&G difference is rougly 10% better fe for p&G if your glide times are much longer than push times. With stock vag aero that works best when speeds are under 90 km/h. So push from 75 to 90 km/h and you will glide roughly 10 to 15 seconds. Push will take on fourth gear 3-6 seconds depending how level the road is etc.

Best way is to test one tank with one technigue on your regular route if you have one. next tank with different technigue or speeds.

Even on my lupo 3l (stock) going from 100 km/h to 120 rises fuel consumption 0.8 liters so speed is your enemy in most cases.

Also there are over 100 tips what effects fuel consumption so it takes long to learn everything as my previous post said I think I learned again one new technigue that was not even yet figured out by anyone at least for me that sounds new technigue?

 

[TDIMeister]

I think a cool thing to have is a rotary knob à la Audi's MMI on the centre console for much finer adjustment of TPS. For most, one's fingers are much more sensitive and dextrous than one's right foot can ever be.

In principle, the circuitry would be very simple; the knob itself is a variable potentiometer and the impedance matched to the desired range of adjustment plus or minus the prevailing TPS signal from the foot accelerator pedal, sort of like the manual up/down speed adjustment on the cruise control stalk but with more fluid and finer control.

 

[TDIMeister]

Another nice thing to have (and someone can freely steal this idea - with due credit given - and make something out of it...) is to have a screen with the engine torque/RPM curve with BSFC contours on it. Then each load speed point can be plotted in, say, 1 second intervals and the last 300 points (5 minutes) of driving will be plotted in front of you to see how your driving style matches with economical driving.

So you'll get something like this:

You want to try to drive in the efficient blue areas or overrun and avoid the red/orange/yellow areas.

While we're on the subject of ideas for fuel-saving gadgets, a stop-start system is quite easy to realise in the TDI and most of the required sensors/values already exist or can be readily determined (VSS, RPM, clutch switch, gear selector, etc.). I'd totally buy a kit to add to my car.

 

[VeeDubTDI]

Another nice thing to have (and someone can freely steal this idea - with due credit given - and make something out of it...) is to have a screen with the engine torque/RPM curve with BSFC contours on it. Then each load speed point can be plotted in, say, 1 second intervals and the last 300 points (5 minutes) of driving will be plotted in front of you to see how your driving style matches with economical driving.

So you'll get something like this:

You want to try to drive in the efficient blue areas or overrun and avoid the red/orange/yellow areas.

While we're on the subject of ideas for fuel-saving gadgets, a stop-start system is quite easy to realise in the TDI and most of the required sensors/values already exist or can be readily determined (VSS, RPM, clutch switch, gear selector, etc.). I'd totally buy a kit to add to my car.

Great graph! Demonstrates very clearly why rapid acceleration followed by coasting is more efficient than gradual acceleration over a longer period of time.

 

[MikeMars]

Well, sure, 75% load is a good point on the BSFC chart, but only some of us have a load meter (scangauge / ultragauge). Everyone else has no choice but to guess.

http://www.bbc.com/autos/story/20130627-a-diesel-vw-tiptoes-to-a-record

... Speaking with BBC Autos, Gerdes said he used a scanning gauge to determine engine load at any given time of his trip. Engines tend to be most efficient at 70% to 80% load, so the scanner helped him remain within the optimal rev range by dictating how much or how little throttle pressure to apply. ...

LOL, the BBC journalist translated 'scangauge' to 'scanning gauge'...

 

[Vekke]

http://www.youtube.com/watch?v=NCvuyMQt9Kc

Some footage of short P&G test on my lupo.

 

[Vekke]

Video of my personal best 2.158 l/100km at 92.7 km/h avg speed. For US friends that is 109 MPGus at 57.6 MPH

http://www.youtube.com/watch?v=CShMRrH-FI8&feature=youtu.be

 

[VeeDubTDI]

Video of my personal best 2.158 l/100km at 92.7 km/h avg speed. For US friends that is 109 MPGus at 57.6 MPH

http://www.youtube.com/watch?v=CShMRrH-FI8&feature=youtu.be

Great results, Vekke!

 

[thomamon]

The videos posted no longer are available

 

[Vekke]

No they should work. Strangely youtube has removed from the link tuneko part :/. post here if there is any other links that dont work so I can correct them.

 

[Jagerbecher]

Side comment. Its not necessary to put the car in neutral if you have very gentle throttle pedal feel. apply just that much gas that your instant fuel consumption sets to to same level as idle fuel consumption in neutral on same speed. Its not totally the same thing as cruising in neutral but roughly the effect is the same. Its safer to be little bit over the idle fuel consumption so you are not "engine braking" the speed off.

I mean engine would need that same amount of fuel anyway. I think it works like that but havent made very scientific analysis yet on this technigue.

Vekke, this is a great tip and makes perfect sence. And I am suprprised nobody yet appreciated this technique. When I shift to N it will still be consuming at least 0.63lph diesel just to keep engine turning and on the down grades it does not make a sence to shift to N until the consumption is more then 0.63lph and the grade is still sloped enough to keep the car in desired speed or slow the car down very slowly. Or, when approaching stop I can set the accelerator pedal to the position that results 0.63lph early and not be slowed down fast by engine breaking or I may get further then gliding in N (i.e. set the idle consumption earlier the i would normally shift to N). I should definitelly try this technique using my scangauge and LPH gauge, as I think it will be much more simple to apply it then using buil in instantaneous MPG gauge. Using the instantaneous MPG gauge I would need to shift to N first to read the MPG and shift back to D (on DSG) to keeps this MPG with accelerator pedal. And that is little bit complicated and requires long enough same road condition.

 

[foggedz]

Thanks for some of your tips. I watched the video you posted in the first post and it seems like a no brainer for driving pretty much any car. I have a 15mi drive to work every morning were I stop 4-5 times on average. The last 2 days on the way to work I made it with out stopping the car once just by keeping my eyes on what is going on ahead of me. It doesnt take any longer to get to work, and the only time I get passes is when someone is blowing past me only to have to jam on their brakes to stop at the next stop light.

 

[Vekke]

If you have regular trip and there is many lines going straight on traffic lights or where you want to go then you can start changing lanes to choose the one which has least cars, or if some lane has trucks or other slow moving object like tracktors etc try to avoid also those. Shorter lanes start to move faster. Try to avoid lanes which has driver who is doing his driving learning at least in Finland they have to have sign to warn other drivers.

That is faster in the long run even you would get through the first lights without stopping in the other lanes that might not be the case in second or third lights.

 

[no-blue-screen]

All good tips. I made a video myself mainly because of all the questions I was getting.

http://youtu.be/zgyjVvEuDLo

 

[Jagerbecher]

All good tips. I made a video myself mainly because of all the questions I was getting.

http://youtu.be/zgyjVvEuDLo

In the video you said that having the CC on you loose the ability to speed up before the hill. I don't think you are correct here. You can step on the accelerator and speed up over the set speed and you can still keep the accelerator pressed at the constant position when driving up hill while the car is gradually slowing down until the speed drops to that set by CC and then the CC kicks in again. You can still keep holding the accelerator at the same position and it will accelerate the car again once you get on the flat or downhill section of the road. This way you can pick up more speed before next incline.

 

[Jagerbecher]

On my last trip I've been trying to follow the rule of accelerating with 80% throttle, and it just seems to me too much. I might be efficient for engine but it seemed to me crazy fast and aggressive and in many traffic situations even dangerous. I found that I feel comfortable doing 50% to 70% throttle. Question: Does't hard accelerating such as over 70% throttle increase the wear of the drivetrain components too much that it may not be worth fuel savings?

 

[no-blue-screen]

In the video you said that having the CC on you loose the ability to speed up before the hill. I don't think you are correct here. You can step on the accelerator and speed up over the set speed and you can still keep the accelerator pressed at the constant position when driving up hill while the car is gradually slowing down until the speed drops to that set by CC and then the CC kicks in again. You can still keep holding the accelerator at the same position and it will accelerate the car again once you get on the flat or downhill section of the road. This way you can pick up more speed before next incline.

Good point...using the pedal to override the CC will allow you to speed up without turning off the CC. Allowing you to gain momentum before hitting a hill.

 

[Oilerlord]

On my last trip I've been trying to follow the rule of accelerating with 80% throttle, and it just seems to me too much. I might be efficient for engine but it seemed to me crazy fast and aggressive and in many traffic situations even dangerous. I found that I feel comfortable doing 50% to 70% throttle. Question: Does't hard accelerating such as over 70% throttle increase the wear of the drivetrain components too much that it may not be worth fuel savings?

I think it's too much too, but I'm by no means a hypermiling expert. With the new MKV6's too much wheel-spin happens when you hammer the throttle down (even more with Malone-tuned cars). I'm using 30-40% throttle on starts which seems to be the right number for my car. That said, I haven't found a big difference in MPG from gradual acceleration and winding up the turbo - but the latter is a lot more fun

 

[puntmeister]

I practice most of the techniques described. With one exception: I am not convinced rapid acceleration to speed is more efficient than gradual, light acceleration to speed.

With almost everything in the world, not just diesel autos - the faster you try to make something happen, the (exponentially) more energy that is required. ie - it is almost always more efficient to gradually do something (anything) than to do it rapidly.

The above is strictly in a theoretical sense - in the sense of having a perfectly clear straight-away, with no obstacles. Starting from a stand-still, and going a total of 5 miles, with top speed of 55mph, would use you less fuel if you accelerated to 55mph rapidly, or gently?

I vote gently. But I would LOVE to be proven wrong.

In a real world sense - in city driving - rapid acceleration will most often hurt you, as you will, on average, end up having to waste more energy to braking. The exception is timing lights - sometimes it will pay to accelerate rapidly to make it through a soon-to-change light.

The above nuanced argument aside, I don't think accelerating technique is the main factor in MPG. The bigger factors:

1) Top speed. MPG starts to go down after 55mph (true on all cars/trucks). MPG drops gradually between 55 to 65mph. Beyond 65mph, and it really starts to tank.

2) Braking. Less braking = better mpg. This is the hardest part, as it ultimately involves a lot of strategy, planning, and concentration - especially in urban driving.

Everything else is relatively minor.

The engine braking versus gliding in neutral arguments found in this thread are generally due to confusion over what everyone is intending to say. Clearly, if you are coming to a stop, slowing down in gear uses less fuel than gliding to a stop in neutral.

HOWEVER, that assumes the same start-point in the road. The argument that coasting in neutral is better is premised on the idea that you begin to coast at an earlier point, ie - you 'read' the situation better....you foresee you will need to stop, and let off the accelerator, and coast in neutral - ideally, perfectly timed such that you come to stop at the intended point of stop without ever having to touch the brakes, or touch the accelerator.

Again, that all plays into the 'minimizing braking' above, which takes a good deal of practice and, at times, a bit of luck.