Z Cars makes the motorcycle powered Mini, one of the most "gotta have" cars around as well as the Tiger. Several configurations are available, both single and twin engined R1 power, Hayabusa and turbo Hayabusa in the Mini and all sorts of Tiger variants.
And just for good measure, their web site says they're working on a conversion for a Smart car. Remember those? Stock power output is 60hp. News Flash!! This just in... The Smartuki has now been built. It's a GSX-R1000 powered Smart Car with 180hp, 0-60 in 4.2 sec. and 12.4 quarter miles. I like it.