PSA: Fuel Consumption

I have seen a couple threads with people complaining about the fuel consumption of the cars, or that the endurance races are hard and the AI are broken because the AI can drive 4 or 5 more laps than the player can. I have just completed the Spa 100 endurance race and did a little experiment and tracked some data.

Highlighted info is wrong see post #5 for additional information. Just a quick forward. The way fuel consumption is calculated has not changed since Forza Motorsport 2, I never played the first one so don’t know how fuel consumption was handled. I have not tested it in this game but in Forza Motorsport 3, all of the cars got the exact same fuel mileage. The only thing that determines the amount of fuel you use is how much throttle you apply. RPM’s do not matter, car speed does not matter, and drafting does not matter. A car doing 5mph at full throttle, a car doing 200mph at full throttle, a car doing 1500rpm at full throttle, a car doing 7000rpm at full throttle, and a car drafting at full throttle all use fuel at the same rate. So for example all of those cars would run out of gas in 50 miles. So the ONLY way to save fuel on Forza is to either drive at below full throttle, or coast into/through corners and use no throttle at all. I did several laps shifting half way through the rev range and it used the exact same amount of fuel as when I was just normally racing.

I play on Pro difficulty and long races, the Spa endurance race is 46 laps I managed to come in 1st place, I only had to pit one time in the race, all of the AI pitted twice. The first half of the race I drove the car like I normally would until I realized I was going to run out of fuel too soon to only pit once then I started saving fuel. At the end of lap 23 (half way through race) I only had 2% of fuel left (averaged 4.26% per lap), the second half of the race I drove conservatively and had 10% fuel left at the end of the race (average 3.91% per lap).

The raw numbers:

My normal racing lap: 4.4%-4.5% fuel consumption per lap at Spa
My fuel efficient lap: 3.9% fuel consumption per lap at Spa
Lap time difference between best lap and fuel saving lap: 3.5 seconds slower
Time to get from pit entrance to exit at race speed: 18 seconds
Time to get from pit entrance to exit by pitting: 40 seconds
Time difference between pitting and not pitting: 22 seconds

Taking 4.4% as a normal lap, at Spa I can travel 22.7 laps before running out of fuel, meaning I would have to pit every 22 laps. So using the 46 lap long race as an example I would need to pit twice (once at the end of lap 22 and once at the end of lap 44). By pitting twice I am costing myself 44 seconds over the entire race. Driving every lap as a fuel efficient lap being 3.5 seconds slower per lap, and only using 3.9% fuel per lap I would need to only pit once (at lap the end of lap 25) The 46 laps times 3.5 seconds per lap costs me 161 seconds over the entire race, and the one pit stop costs me 22 seconds. So driving every lap as a fuel efficient lap is 139 seconds slower over the entire race. So you would not want to do that.

If instead you came up with a pit strategy and decided you were only going to pit one time but drive as fast as you could to do that, you would drive the 20 normal laps and 3 fuel efficient laps to pit at the end of lap 23 with only 0.3% fuel left. You would then drive 20 more normal laps and 3 fuel efficient laps and finish the race with only 0.3% fuel left. By doing this the 6 fuel efficient laps would cost you 21 seconds, and the one pit stop would cost you 22 seconds. So this strategy means you are 1 second quicker over the entire race than you would be if you just drove flat out and pitted twice.

If we switch to an 69 lap extra long race. Driving flat out means you have to pit 3 time costing you 66 seconds. With a pit strategy to only pit twice you would want your final pit stop to be at the end of lap 47, so you would plan your first pit stop for the end of lap 23. With this strategy you would drive the first 20 laps flat out, then do 3 fuel efficient laps, then you would pit at the end of lap 23 with 0.3% fuel remaining. Then you would do 19 flat out laps and 4 fuel efficient laps and pit with 0.8% fuel remaining at the end of lap 47, you would then drive 22 more flat out laps and finish with 3.2% fuel left. By doing this the 7 fuel efficient laps cost you 24.5 seconds, and the two pit stops cost you 44 seconds. Meaning by only pitting twice you are costing yourself 2.5 seconds over the course of the whole race.

On the 23 lap short race, driving flat out will only require 1 pit stop at the end of lap 22 with 3.2% fuel left, costing you 22 seconds. Running the race without pitting would require you to run the first 20 laps flat out, and the last 3 laps as fuel efficient laps to finish the race with 0.3% fuel left. Those 3 fuel efficient laps cost you 10.5 seconds. So by not pitting you are saving 11.5 seconds over the entire race.

So based on the way I drive at Spa, pit strategy does not matter for me at all unless it is a short race. As on an extra long race only pitting twice takes 0.036 seconds longer per lap, and on a long race, pitting once only saves 0.022 seconds per lap. On a short race by not pitting I would be saving 0.5 seconds per lap.

Someone better or worse than me at the game may have completely different results, and there is no guarantee that my method of coasting into the corners is the best method to save fuel, or that the amount of fuel I am saving per lap is the best amount to save, and who knows maybe Spa is just a bad track to try to save fuel on? I did have fun though keeping track of my fuel usage during the race to ensure that I did not run out or have to pit twice.


Interesting report. I wasn’t aware that fuel mileage wasn’t simulated per-car.

However, a factor you don’t seem to be tracking is tire wear. Newer tires are faster than older tires. (You can accelerate faster and you can break faster, which lets you start breaking closer to corners.) Since there’s no such thing as a fuel only stop in Forza (every stop changes four tires), the earlier laps in a run should be faster.

I do most of my endurance racing on ovals. And at Homestead, Daytona, and Indy, (at least) the way to beat the AI is to pit when your tires are worn, not when your fuel is low. Since the AI seems to be pitting based on fuel, you get the benefit of a few extra (faster) laps on fresh tires.

Good analysis.
I think the GT cars are pretty close to one another as far as laps per tank of fuel.

I’ve noticed the biggest issue seems to be in LMP1 cars.
At Le Mans:
The Nissan gets 3-4 laps per tank.
The 919 and R18 gets 6-7 laps per tank.
The 908 and R15 gets 10-11 laps per tank.

So, for an example, in a 20 lap race the 919 has to pit 3 times vs. 1 time for the 908.
That means the 908 has over a one minute advantage already built in.
That translates to 3+ seconds per lap.

I don’t think all cars get the same range. The Nissan GT-R gets about 10-15% further than the Acura NSX FE, for example. I do usually 125-135km races in freeplay. The NSX can’t really get to 135km without doing a 2nd pit stop. The GTR can do it easily. Maybe 150km.

But All the drivatars seem to somehow get another 30-50% further! Something is wrong there!

Correct. I’ve reported on this on occasion before. The difference between cars even within the same class can be staggering. Players playing longer races with fuel simulation are limited to specific cars in some classes, if they want any chance of victory. For example, the Ford Gymkhana is useless if you’re running anything but the shortest race distances, no matter how you drive, because other cars in class can run flat-out and go several laps farther before pitting. As an illustration, I think a race at Maple Valley was ten laps and the Gymkhana needed fuel by lap seven, whether me or AI, while other non-Gymkhana cars made it to the end without pitting. I don’t know if a player could lift and coast enough for all ten laps to get like 40% more distance out of a tank so as to not need to pit.

T10 may also be simulating fuel tank sizes. Did a quick google search on fuel tank sizes for the GT-R and NSX.
Nissan GT-R fuel tank size - 19.5 gal.
Acura NSX fuel tank size - 15.6 gal.

The GT-R’s fuel tank is 25% larger. If that info is coded in the game, then even if both cars burned fuel at the same rate you’d need to pit sooner in the NSX because of the smaller tank. Something to consider especially with the race car divisions that include cars from different eras that were built under differing regulations.

So just did a quick test at Daytona

After 3 laps:

The Nissan has 95.4% fuel left
The 919 has 84.3% fuel left
The R18 running in 5th has 88.4% left if you run it in 6th you have 88.8% left if you run it in 7th you have 89.2% left

Which raises the question does RPM actually mater or is it just based on gear choice? So I ran it in the #10 Chevy Prototype

Stock after 3 laps 89.0% fuel left
Longer 6th gear, made top speed about 170mph after 3 laps 91.2% fuel left
Tuning 5th to be the same as stock 6th gear after 3 laps 89.1%
Tuning 6th to gear limit the car at 170mph and running full throttle after 3 laps 90.4% remaining. It is worth noting in FM7 you can not hold a car on the rev limiter without the game cutting throttle and slowing you down about 10mph.

Gear limited at 170 but partial throttle to hold car at 170mph after 3 laps 91.3% fuel remianing. It ended up being around 80% throttle the whole time.

So it seems like RPMs actually do matter this time around for fuel mileage, as well as throttle position.

And just for fun a stock 1994 Miata ran at 60mph in 5th gear. My real life basically stock engine 97 gets right around 32mpg doing this. After 3 laps 98.2% fuel remaining. Assuming the stock 12.7 gallon tank that means it used 0.2286 gallons. 3 laps around Daytona is 7.5 miles. That equals 32.8mpg. Now the question is that a coincidence or did T10 actually model fuel data for vehicles? The homogolated 209hp version gets the same fuel mileage running 60mph around daytona with a stock transmission.

So 2012 Jeep Wrangler, real life highway mileage 21mpg according to the internet. Fuel capacity 18.6 gallons. After 3 laps 97.7% fuel remaining. That equates to 0.4278 gallons, giving 17.5mpg which is a little on the low side.

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I think the LMP2’s seem to be pretty closely matched to each other in fuel consumption, like the GTLM’s.
Both classes seem pretty close to real world performance.

The cars that appear to be screwed up are the Nissan LMP, R18’s and 919’s. (Based on racing a Le Mans.)
(I’ve never hit the rev limiter with any of those cars.)
I did find that if you cut the 919’s down-force roughly in half (from stock) you can get an extra lap out of it - from 6 to 7. (Which makes sense.)
It’s still off from real world performance by 4+ laps and in game performance of the 908’s and R15. (Which get 10-11 laps per tank.)

Of course all of this is kind of moot as I just discovered you can force the number of pit stops when setting up the race.

Regarding the LMP1 cars, has anyone tested whether lower downforce equates to more fuel efficiency? For example running a completely stock tune opposed to a stock tune with minimal downforce? In the real world, less downforce or less drag is more fuel efficient. Does anyone know if this is simulated in game?

After some testing with different cars I came to the conclusion that neither RPM nor throttle position is important but the pure power your car is releasing. For example if you upgrade an engine to more power output the same car will consume more fuel. In fact you could reduce fuel consumtion by lifting the throttle a bit and by shifting earlier but this is only because then you have a lower power output.

Our experience with 45 minute races was that we have constant lap times and neither fuel weight nor tire usage have an effect until the tires reach 60% usage. Some of our drivers report lower lap times when reaching 30% usage but I guess this effect is due to lack of concentration over time.

It is simulated and it doesn’t only count for prototype cars. Also a street car uses more fuel when it is upgraded with splitter or wing. Fun fact: Even in Forza Motorsport 2 downforce has an effect on fuel usage.

That’s interesting. I owned and played FM2 but never noticed it. It’s good that downforce does effect fuel consumption, I’m pleasantly surprised by that. I’ll run some tests soon and see what data I get.


I am curious as to why all the cars in Forza 7 are exceptionally Fuel Efficiency while racing? For example, the Fuel Efficiency for all wheel driving cars really stand out and they seem to sip gas lap after lap when driven hard.

This brings me to another question I have. If you are driving hard during a race shouldn’t it reflect on the amount of gas consume? The harder you drive the more gas is consumed. I’ve only seen one occasion where there was about 1/2 tank of gas left while I was racing. I think it was a rivals event (over 15 or so laps I think). That’s what made me ask here. I saw it for the 1st time.

Or is it that for Forza 7 gas consumption isn’t really a concern? I ask because I don’t know of any information in a manual to refer to for stuff like this.

[Mod Edit - thread merged, see above - MM]

one thing I would like to point out. Mileage in real life racing/driving is heavily dependent on throttle position, breath the throttle more, get better economy. SOmetimes you can go as fast or faster using the lift early, ease back into it approach as you can mashing the pedals constantly. it may not be ,modelled perfectly, but I know that theory does apply even in Forza.

I go full throttle on the exit of every corner that allows for it. So I’ve never noticed that. Therefore, I have to respectfully disagree. Furthermore, it’s easier to do on AWD cars so there is very little to no downside. AWD cars in F7 have a huge advantage in handling vs RWD contenders.

That is simply just BS.

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Drafting does matter, I did a test on daytona myself, I went 10% further while drafting compared to when I did not.

Milage is also displayed separately for each car so I don’t know what you’re talking about at all and it makes me want to try and disprove this. (the part with drafting not affecting anything is already disproven since I’ve already done that test and saw 10% savings on gas.

i can not confitm same fuel consumption on different cars. At Le Mans in the Forza P1 Class the Audi 18’ has a range of 8 laps, the Peugot 12 laps (not sure about the porsche - think 6 laps) all the same driving style (as fast as i can - not taking care bout fuel or tires) AI at 80%, no change on build no tuning, handshift without clutch, all assistents off, brakeline (?) on.

What I think is being lost in all this is how T10 is walking a strange line with regards to realism; if what people are saying here is accurate and there are ways to drive to improve your fuel economy – as there are IRL, both on the track and the road – that’s a pretty heavy dose of realism. Yet, they can’t let us qualify, because – as I’ve read here and elsewhere – that adds too much of a realistic “grind” to the game? I’m sorry, but that doesn’t truck with me. Can’t have it both ways, far as I’m concerned.

Have to thank you for this post! I just started the extra long laps in single player, and bumped up to pro after lapping the field in my last race. Big difference on pro is that most of the AI don’t pit on 20 lap races (but will on 30- 40 ones). After running out of fuel on lap 19.5… I found this post and tried it out. Drove like hell the fist few laps to get the lead, then coasted 50m off my breaking points and eased the throttle coming out of the turn. Was a pain having the AI full my mirror the whole race, but I did my best Daniel Riccardo at Monaco impression and hogged the apex and kept the whole AI procession behind me.

Thanks again for the post! :+1: