Out of curiosity, did anyone else collect the Custom Motors
line from Hot Wheels? I collected the full set, and I think they're pretty cool personally. The basic principle is that each vehicle has a set of parts that can be removed and modified, and most parts are interchangeable between all of them. With one exception (the Tumbler version of the Batmobile), they're all original vehicles.
I believe they're no longer being produced, as I haven't seen any for some time, but I think one can still find them through sources like Amazon and other online dealerships.