Daredevil Dragster

A 4/4 body for three generic mana that pays you to keep attacking, then takes itself away before you can overuse it: the velocity counters accrue at end of combat, and the swing that lands the second one is also the swing that ends the car's life. That math is the whole design. The Vehicle only ever fights twice, because the combat that brings the count to two triggers an immediate sacrifice and refunds you two cards. There is no third lap. The clean line is two attacks and a draw, but the sacrifice is not yours to schedule: it fires whenever that second counter arrives, even on a defensive block you would rather have kept the body around for. The refund-on-death structure also denies an opponent the satisfaction of killing it for value, since it converts to cards on its own clock rather than theirs. Crew 2 is cheap enough that any pair of small attackers turns it on, so the running cost of the engine is a couple of taps. It belongs to a line of artifacts that draw cards across turns rather than in a single cantrip flash: a threat you grind value off of while it does its job in the red zone, a body that knows it has exactly two laps in the tank and spends them deliberately.