When all else fails..use clipart. I don't have any cars in my large stash of stamps so I found a clipart that suited me just fine. One of the owners of the local stamp store told me a while back that when guys look at cards they see solid colors, greys, black, browns and blues. Keep it simple, maybe that is why I seem to pull of masculine card so easy. I am not sure I should trust him though, I have seen him make cards with Pink Flowersoft (I don't think that particular card was for a guy :))
For the inside (sorry no picture) I put two matching layered strips down either side, and put a popped up steering wheel in the middle.