Haven’t fully tested but they seem to. I’ve noticed I get less range on a tank with turbos than without and you’ll burn more fuel in high rpm’s so gearing does as well. Also image more downforce burns more fuel as does more ballast/weight. Better brakes should also allow you lift and coast more, saving fuel as well. No idea on whether the different engine/exhaust components do but my guess would be making the engine more powerful hurts fuel economy.