I know if you beat a level a second time with fewer stars it shows in the level selection menu and that's kind of a "reward". But sometimes I want to replay a level with more stars, especially when I want to use a new vehicle, but it's a little discouraging if there's no permanent recognition for doing so. So I'd suggest perhaps displaying how many times a level was completed or giving completion points even for completing a level with more stars (more points for completing with fewer stars). Just something to make note of the accomplishment.
Anyway - the more statistic we have, the better. Now MR is 100% pure, no statistic at all!(
Even no truck stats.
Such purity have some positive sides - you dont blow your mind - take ural 375 or ural 432010, you just take it.
But mature games, like MR2, must have stats.
Incl number of stage completion (with some rewards maybe), total mileage done at this stage, fuel burned, time spent and so on.
Separately the same stats for trucks - its total mileage by player, and so on.
Now i save all above stats at excel sheet.