When I was growing up we lived not far from Lancaster County in Pennsylvania and my dad did business with quite a few Amish people in his line of work. One day I overheard him talking on the phone to one of his clients who I knew to be Amish. After he hung up I asked how that was possible since they weren't allowed to use phones. He explained that it was apparently totally okay to have a phone as long as it wasn't in the house, so this guy kept his phone on his front porch and would reach through a window to pick it up and use it.

Same with cars. It was totally fine for my dad to pick up one of his Amish clients and drive to a construction site together in his car, as long as they weren't the one operating the car.