I would worry about repeatedly having a 'gimp' due to jumping out of the car... that sounds like a recipe for early onset arthritis or something worse.
Backing into a bank sounds like a good solution, to me. HA!
You could work on having him 'wait' until you put down a soft landing pad or extra stair for getting out of the car, to make the 'jarring' of the landing less. Ramps or stairs would be a definitely plus - and will probably come in handy as your pup ages into a senior (as we hope they all will someday in the distant future).
Denna used to hop into the back of the Subaru, and never had a problem jumping out of the back, either. Since her back knee injury, we have her climb in and out of the back seat. She uses the door jam as her 'step' and sometimes will get her front end in and wait for me to give her hind end a 'boost'.
We're also in the market for a ramp, as our dog-walker's car doesn't have the built-in step that our Subaru has (she doesn't go in via the back seat in her car), and she occasionally picks Denna up from where she boards.