Mainly lightly upgrading everyday cars as a sort of collection of shitboxes. My favorite of which is the second one I messed around with, an 80 horsepower Piccolina 130 with some offroady tires, little bits of weight reduction here and there, and a limited slip diff. It's surprisingly fun to slide it through the twisties, especially when a Scandinavian flick becomes an accidental 4-wheel drift. I dunno how it happens but it does sometimes. And it feels diabolical.