Does weight of fuel actually affect vehicle performance?

[Famine]

One doesn't have to look hard through GTPlanet to find threads of folk suggesting that their car is faster with a lighter fuel load...

GT6
GT5
GT4

A full 100 litre fuel tank will weigh around 73kg (88kg if diesel), which wouldn't be so much of a dent in a 2 ton Mercedes SL, but would be quite the weight saving in a GT300 racer and a fifth of the car's weight for an LCC Rocket! That should produce a significant difference in laptime and grip if it is indeed modelled.

I've not seen anything in playing Gran Turismo to suggest it happens, though with endurance races you're typically running low fuel loads on old tyres, so it may be offset by the worse grip.

But does it?

 

[sparkytooth]

I've never experienced it myself actually. I think it's more of a placebo effect.

 

[gitslautriv]

I guess changing tyres without topping up fuel is the only way to find out (without working for Polyphony of course).

Who's got time to waste on their hands...

 

[sparkytooth]

I guess changing tyres without topping up fuel is the only way to find out (without working for Polyphony of course).

Who's got time to waste on their hands...

I used to do it on GT5 when I was in Global GT. Since they weren't very long races, only the tyres took a reasonable hit and needed change. I don't remember if I did get faster.

 

[SagarisGTB]

In GT5 it clearly does. Probably GT6 too, but I digress, I know you'd rather Kaz answer than me.

I have a similar question, though less important. I was wondering if the "driver" in GT6 weighs anything in the physics calculations. For example, if a GT500 SC430 weighs 1100 kg on the track (in which case, the driver would have a mass of 0kg, which I'd assume is the case) or if the weight is closer to 1150, or more if fuel is also part of the calculation. As Famine says, not so important for heavier cars, but every kilo is vital in an X-bow and I would be curious to know the exact weight of the cars for the sake of comparisons to reality.

 

[TRLWNC7396]

Very good question here. +1

 

[TT92]

I guess changing tyres without topping up fuel is the only way to find out (without working for Polyphony of course).

Who's got time to waste on their hands...

This now has only been possible since update 1.07 and the (apparent) fixing of the pit stop tyre glitch.

From my experience in endurance races so far, fuel load has *NO* effect on the cars performance. Although, I think it definitely should.

As well as for qualifying you should be able to adjust fuel load to set your time - just like in real life ;-) But then, one would only expect this from a *REAL* Driving Simulator not just an arcade game like we have.

 

[nascarfan1400]

I have laid down faster times aswell as @ITCC_Andrew in some long ITCC test sessions on a lower tank before... But then agai there's a ton of variables with that.

 

[Furinkazen]

It has a massive difference. Was driving FGT's around Indy Oval in a 700hp, 700kg spec and hit consistent 40.4's. Pitted for new tyres, and with under 50% gas in tank did 40.2's. Car feels lighter, more responsive and it does alter the balance a bit. I've also had similar in my Ford MK IV at Matterhorn. Despite being 20hp from race start due to oil being dirty, was lapping 0.5+ seconds a lap quicker on Dristelen with low fuel.

 

[Mini Stiggy]

I have no doubt that it does. Simple example: T1 at Silverstone. With a GP2 spec FGT. In the beginning of the race (max fuel), there is no chance at taking it flat out. When I had low fuel however, it could be taken flat out. Plus lap times were significantly faster.

Edit: Tree'd by another example with a FGT

 

[ITCC_Andrew]

I once qualified on a 5 litre lap... (5 litres left)

Everyone was confused about how I did it. I'd say it definitely does.

 

[nascarfan1400]

Dawww I thought it was just me and Andrew learning the track

 

[ITCC_Andrew]

Dawww I thought it was just me and Andrew learning the track

Nope. I qualified on pole by like a second and a half at Tokyo R246 round of Continental Tire Sports car Championship in GT5, on my way to my only championship, nas. I had the fuel light come on the lap after.

If I hadn't won that race, I would've lost the entire championship, so that qualifying lap was a display of my best driving. and strategy... In that I pitted for tires, but picked up 0 litres of fuel.

 

[nascarfan1400]

Nope. I qualified on pole by like a second and a half at Tokyo R246 round of Continental Tire Sports car Championship in GT5, on my way to my only championship, nas. I had the fuel light come on the lap after.

If I hadn't won that race, I would've lost the entire championship, so that qualifying lap was a display of my best driving. and strategy... In that I pitted for tires, but picked up 0 litres of fuel.

Your telling me that you've only won one championship on GTP!?

 

[ITCC_Andrew]

Your telling me that you've only won one championship on GTP!?

Yup

 

[Goruk]

Last saturday I had a GT300 1 hour race with a mandatory pit stop between 25 and 35min of race.
I was driving the Arta Garaya, and before the pit stop the car was a bit tail happy after mid corner, after the pit stop, and with half a tank I felt the car a lot more composed and I cloud brake later for the corners, what led me to improve my best lap in almost a second.
Now if the fuel tank is somewhere between the midle of the car and the rear, I can tell that you feel the diference in the fuel load.