List the cars you’ve used during endurance races and how many laps you could go without pitting.
Road Atlanta-Lamborghini-22 laps-1 stop
Nurburgring-Viper-4 laps-1 stop
Le Mans-Audi r18-4 laps-7 stops
Sebring-Audi r15+±14 laps-5 stops
Sebring-Audi r18-9 laps(possibly 10 I chickened out)
Road Atlanta - C7.R - Pitstop at the end of lap 21 - 1 stop
Nürburgring - C7.R - Pitstop at the end of lap 4 - 1 stop
Spa - MP4-12C GT3 - Pitstop at the end of lap 12 - 1 stop
Catalunya 100 - MP4-12C GT3 - Pitstop at the end of lap 18 - 1 stop
Nurburgring 125 - Viper GTS R - Pitstop at the end of lap 4 - 1 stop
Catalunya, end of lap 19 in the lambo, but I had to drive conservatively in the last half of the lap, it was one stop for me, most of the racers had to two stop
I done the Nurburgring in the Bentley and pitted at the end of lap 4, but ran out of fuel just as I exited the last corner and only just made it into the pits, then on the final lap had to drive really, really conservative to reach the finish.
Road Atlanta -458 - 19 laps - 1 stop
Pushed quite hard in the first stint to get a good gap between me and 2nd place. Had to manage fuel and tyres for the second stint to maintain the lead.
Catalunya - Gallardo - 21 laps - 1 stop
Pushing majority of the time until the end where i gave up and settled for 2nd. The lead drivatar was miles ahead of everybody
Road Atlanta-Bentley-21 laps-1 stop
I can tell you you can get 10 laps out of the R18 at Sebring just don’t try for 11 like I did, ran out of fuel on the back straight & luckily I was able to roll the rest of the way but spent the next 30 - 40 laps fighting back.
I was racing the r18 right after running out of gas in the r15 so I wasn’t pushing it.
Flat out I got 10 laps as well. About midway through the race I decided to try a fuel conservation run so I could avoid having to do a full pit stop with two laps to go. I spent the stint short shifting between 3000-3500 rpm and letting off the gas early to coast into the braking zones at the end of the straights. Managed to eek out 12 laps. Lap times suffered a bit but I believe I still came out ahead by not having to do an additional stop.
Mod Tip: I equipped super rare Driver Mastery and Windfall mods for 100% XP and Earnings bonuses. The race took 2 hours and 46 minutes but I jumped 13 levels and made 3,109,450 in credits and prize cars.
Le Mans Ferrari F-50 50 laps Pitstop EVERY 4 laps!
Spa Ferrari F-50 50 laps Pitstop every 6 laps
Le Mans Ferrari 333SP 50 laps Pitstop EVERY 3 laps!
Spa Ferrari 333SP 50 laps Pitstop every 4 laps
Le Mans Lotus 49 50 laps Pitstop EVERY 4 laps!
Spa Lotus 49 50 laps Pitstop every 6 laps
Le Mans Ford GT 50 laps Pitstop EVERY 3 laps!
Spa Ford GT 50 laps Pitstop every 4 laps
Most other tracks in the 10 to 20 laps per race same cars. Same dismal fuel mileage
Apparently ALL of my cars have fuel tanks the size of a weasel bladder!
Having to pit so often means I HAVE to run qualifying lap times throughout the race due to loss of time in the pits. One of my two pet peeves in Forza 6. The other? Why no qualifying? Not even a single flying lap to be had.
These laps are all full sinulation turned on, 23 opponents set at Pro level. I won all but two races and both of those fails were in the Lotus 49.
Thrustmaster TX Wheel, T3PA Pedals,
It seems Turn 10 does everything in extremes.
In previous titles players complained that the fuel consumption was comically low. Everyone wanted better fuel consumption models. Turn 10 have turned around and given us fuel consumption we can see but now cars are running out of fuel all the time.
Careful what we wish for, huh.
Can’t wait to have some time over the weekend to try these endurance races. 
Catalunya 100 - #35 SLS - lap 18 - 1 stop
Road Atlanta 100 - #18 Gallardo - lap 22 - 1 stop
Catalunya
Lamborghini Super Trofeo
Pitted Lap 18 and was still in front after my pitstop with difficulty turned up to Pro
The last few laps i was slowed by lapped traffic crashing on the last Left/Right Chicane
Catalunya 100 - Audi - 2 stops laps 16 and 26. Ran out of gas on lap 17
Atlanta 100 - Corvette - 1 stop - 1 lap past halfway
Nurburgring 125 - BMW - 2 stops - after laps 3 and 6 - AI stopped every other lap
Indianapolis 250 - Chevy & Honda - 5 stops - 17 laps per stint
Spa 100 - Dodge Viper - 1 stop
Le Mans - Peugeot - 4 stops - 6 lap stints
Daytona - Peugeot - 5 stops - 14-16 lap stints
its not just the car, its the tune and driving style as well. fuel is energy. the tine walls flexing absorbs energy so the harder a tire is the better fuel efficiency you get. thats why those cars that get 50 mpg have 60 psi tires rather than the 30 psi i grew up with. the higher your engine revs the more gas it uses. short shifting gets much better mileage. every time you use the brakes that wastes energy converting potential distance into heat. the more down force you have the more fuel you’ll use…
and pi it was unrealistic. you could go thru the entire career of fm4 and fm5 without ever having to pit once the entire game. tracks have pit lanes for a reason, they are needed unless its one of those solar car races. not even racing if i dont stop at a gas station every week or two i am going to be walking. its unrealitic to drive a million miles and never once have to stop for gas lol. my wallet wishes f,4 amd 5 were correct, but sadly they are not even close to reality. if people dont want to pit there is an option to turn fuel and tire usage/damage off. in fm5 i tried to use rivals to get the run out of gas chevo on indy. ran out of tires at about 90 laps and slid down the bank in turn 1. didn’t have enough grip to get back on the track or go forward so i couldn’t use any more fuel. trying to run out of gas you usually couldn’t. ended up useing the atom.
Road Atlanta - Bentley GT - 22 laps, 1 stop
simple, just use cosmetic damage on endurance races (idk I dont wanna risk running out of gas and then restarting the entire race)
Road Atlanta with the vette C7R = pitted at the end of lap 24.
Road Atlanta Bentley GT3 end of lap 23, flat out for first 13 laps lifting and coasting and rev limited to 5.5k for the next ten.
If you do Catalunya in the McLaren P1 12C GT3, be careful. There is no fuel indicator on the wheel or anywhere else for that matter. Frustating to say the least. From experience (depends on your driving), I had to stop for fuel at lap 20.
Fuel should be somewhere on the HUD or at least in the telemetry data.