Thought of something the other day, seems quite good, but perhaps hard to implement... But anyway...
Engine modes would be great, something that we can change during the race too, maybe setup on a dial of some sort. So that you can adjust Engine power with fuel consumption and another value too. But each setting will have a down side, higher power=higher wear etc. Maybe make an option under the 'team' part where you can make some pre-made settings on inlaps and outlaps and just general laps where perhaps you can save some fuel and try and run an extra lap. Could bring in some strategic play and generally makes it more fun IMO.