underbody

noun

1. The underparts of a bird or animal.
2. The underside of a vehicle.

   ““There was somebody’s entire fender or underbody on the racetrack,” he said.”

   “The rest were undergoing special underbody cleaning safety checks at TfW depots, after speculation that the cause of the incidents may have been a build-up of engine oil and combustible material such as fallen leaves and general detritus.”