Car buying/renting...then the option to change cars is up to the racer. (as long as he finishes fairly low)
Just sayin'
I'm not a big fan of having to think or strategise too much, TBH.
You're kidding, right? All you do is think, think, lately
Besides, you can just grab the fastest you can get every round if you like.
But let's be honest, it leaves more choice in the hands of the racers, they've more freedom (within limits) to chose their car. It has worked really well in the past for widely mixed fields, even. It's just a matter of pricing the really fast cars high enough.
IMO it adds an element of fun to it, not and element of burden