Better Fuel efficency (after ECE tune)

[Bassik]

Now I've had some confusion on this for a while and have always speculated the how's on many people having said that after getting a tune they see better fuel km/L?

How is this possible?

Personally from me jumping from a Polo to Golf I've noticed a massive increase in fuel comsuption I know it's a 2L vs 1.4L but logic says bigger engine + more throttle = petrol hungry which I get but a tune would naturally increase this torque and HP from a stock car. So in turn wouldnt this mean logically speaking same throttle applied to a tuned car would cause more fuel comsuption? How are people making claims that after a tune I'm seeing better fuel comsuption?

Logically it doesn't make sense, maybe some people can clarify?

PS: I also realise that this could belong in the ECU tune thread however I'm also looking for posts regarding tunes on Golf GTI mk6.

[Finance_Analyst]

From what I know, it is the air/fuel mixture being more optimal, also the extra torque so the car runs in a higher gear, not dissimilar to a diesel which has heaps of torque relative to a petrol car.

[Dutch77]

I'm probably using around 1.0l/100km more on average since being tuned, but some of that no doubt relates to the want of using the right foot a little more. Given the performance gain its a small price to pay in my eyes, although I don't crack 10k a year so fuel usage doesn't really impact me anyway.

Like you I'm pretty sceptical of some performance tunes claiming increased economy.

[h100vw]

Less gear changing, no need to drop a gear to accelerate on the Highway. The car companies have to submit vehicles for type approvals and emissions testing.

These tests are conducted in the same manner for all vehicles. So the consumption figures you see on window stickers at the dealers are working from a level(ish) playing field.

So no manufacturer is going to want to produce some hideous numbers, compared with the competition, that would affect sales. No what the test involves, they will write the code for the ECU to make the most of the test. Who drives at exactly 75kmh ever for a whole tank of fuel? It's like the opposite of EPO in cycling

Yet that's the kind of test you are looking at. So VW etc will lean off the mixture and modify the code to produce the best numbers at that speed. I am sure you have read about complaints of "flat spots in the mid range" of certain cars. These have been engineered in there to play the emissions game.

Tuned software eliminates the deliberate tactics to win at the emissions game and fills in the holes in the power and torque. Making the cars easier to drive and more efficient overall.

The cars have to be able to cope with owners who don't service their cars, who put 91 octane fuel in when they should use 98. These are variables that the VW etc can't control so the software is written to account for this. Tuned software is always written for the best fuel available being run in a well maintained car.

Hope that helps explain a bit of what is going on.

@Dutch77 my Polo, which is up on blocks..... Had pretty grim consumption running on the VW tune, I never saw any of the numbers that it produced even with the Frankenturbo and Phase 3 tune. That's pretty poor when the FT made almost double the power of a std car.

While at any particular point in time it could be using twice the fuel. When you weren't gunning it, the fuelling was so much better that it would use less. The consumption over a full tank didn't change.

[Bassik]

Less gear changing, no need to drop a gear to accelerate on the Highway. The car companies have to submit vehicles for type approvals and emissions testing.

These tests are conducted in the same manner for all vehicles. So the consumption figures you see on window stickers at the dealers are working from a level(ish) playing field.

So no manufacturer is going to want to produce some hideous numbers, compared with the competition, that would affect sales. No what the test involves, they will write the code for the ECU to make the most of the test. Who drives at exactly 75kmh ever for a whole tank of fuel? It's like the opposite of EPO in cycling

Yet that's the kind of test you are looking at. So VW etc will lean off the mixture and modify the code to produce the best numbers at that speed. I am sure you have read about complaints of "flat spots in the mid range" of certain cars. These have been engineered in there to play the emissions game.

Tuned software eliminates the deliberate tactics to win at the emissions game and fills in the holes in the power and torque. Making the cars easier to drive and more efficient overall.

The cars have to be able to cope with owners who don't service their cars, who put 91 octane fuel in when they should use 98. These are variables that the VW etc can't control so the software is written to account for this. Tuned software is always written for the best fuel available being run in a well maintained car.

Hope that helps explain a bit of what is going on.

@Dutch77 my Polo, which is up on blocks..... Had pretty grim consumption running on the VW tune, I never saw any of the numbers that it produced even with the Frankenturbo and Phase 3 tune. That's pretty poor when the FT made almost double the power of a std car.

While at any particular point in time it could be using twice the fuel. When you weren't gunning it, the fuelling was so much better that it would use less. The consumption over a full tank didn't change.

So your saying the testing that VW do is just sit on a dyno and max out @ 75km/h for a whole tank of fuel, I find that hard to believe?

I understand the issues with the flat spots I get those now in the Golf where as in the Polo it was a lot more gradual, no turbo lag or anything however the flat spots in the Polo in drive mode was horrible, constant gear changing.

So a tune would in fact be fuel efficient but it all depends on how I drive it?

My concern is who gets a tune and doesn't drive spirited lol?

[h100vw]

So your saying the testing that VW do is just sit on a dyno and max out @ 75km/h for a whole tank of fuel, I find that hard to believe?

I understand the issues with the flat spots I get those now in the Golf where as in the Polo it was a lot more gradual, no turbo lag or anything however the flat spots in the Polo in drive mode was horrible, constant gear changing.

So a tune would in fact be fuel efficient but it all depends on how I drive it?

My concern is who gets a tune and doesn't drive spirited lol?

European emission standards - Wikipedia, the free encyclopedia I can't be bothered to read all this but you maybe can.

What they do on the dyno is run simulated urban, extra urban and highway profiles and measure consumption. I meant that advertising the consumption at 75kmh means nothing in reality. It's one speed and not how the customer uses the vehicle.

[kaanage]

So your saying the testing that VW do is just sit on a dyno and max out @ 75km/h for a whole tank of fuel, I find that hard to believe?

No, Gavin is saying that is the sort of effect that the manufacturers achieve when optimising for the fuel consumption tests - the exact tests are supposed to be secret but the manufacturers have a pretty good idea of how they are conducted and optimise for the type of simulation that is run.

So a tune would in fact be fuel efficient but it all depends on how I drive it?

My concern is who gets a tune and doesn't drive spirited lol?

Absolutely - my TDi has 25% more power than stock yet in normal driving, I get a 5% improvement over the stock tune.

[Bassik]

Ahh ok so everyday driving is where the fuel consumption matters however if you thrash it your going go through more fuel.

I guess in that I understand that gear changes, throttle flat spots are where everyday driving would consume more fuel where as a tune will reduce this?

[Ryan_R]

More of the propulsion comes from air (boost) lower down in the rev range in normal driving, therefore less fuel is being used. Of course you're going to drive a lot quicker now that you've just got it but you'll settle down eventually.

[Bassik]

More of the propulsion comes from air (boost) lower down in the rev range in normal driving, therefore less fuel is being used. Of course you're going to drive a lot quicker now that you've just got it but you'll settle down eventually.

Hopefully I settle because I'm concerned at the drinking levels my car has with petrol. What people averaging out on. I'm currently at 9.5L/100