Great car for La Sarthe. Though I'm a bit confused by your fuel usage. What's your basic setup (tires, HP, Weight), and what fuel map did you use? Mine is running on Sport Mediums, 512hp, 2500 lbs (1134 kg). I can easily get 3+ laps out of it. It's not by any means the fastest car around La Sarthe (if you're getting sub 4:00 you're doing great), which made for a more interesting race than the usual Le Mans domination (such an easy race...lol), but I didn't have any trouble with the fuel, really. I just set it at fuel map 6 and forgot about it.
BTW, I literally just last night installed that exact same livery from Imbissbrunto, right before taking it to La Sarthe. Great minds think alike, eh?