"Explode race cars" is an objective in the sidequest Clan War: First Place in Borderlands 2.
Walkthrough[edit]
So you want to blow up all the cars in a single go? This can be very tricky to pull off. You need to wait for all the cars to be in the bridge as you hit the plunger for the detonator. it is a very narrow window but it can be done. Just watch for the third car getting onto the bridge and detonate it immediately after.
Any you missed now have to be destroyed by you without the aid of the explosives. This is why the light runner is so helpful. You can chase after them on the track and just gun them down with it. Another option is to simply use a Rocket Launcher or other high powered weapon and blast them away.
