it occurred to me... the best door handles for a car related business with double doors is

the clutch and brake pedal on the door that swings out (on the left typically (in the USA))
a gas pedal on the door that swings in (typically on the right)

If this has already been done, I'd not be surprised at all. In the past decade I've seen several companies put cool and relevant door handles on the business.

REI had a mountain climbers ice pick for a door handle, Hard Rock Cafe has a small brass guitar