My only concern would be warranty issues/accountability if there is a problem down the road, but would love to not have to take the time to go somewhere and get my oil changed.
The idea is the same as a doctor making a house call. You could schedule to the customer's needs either at home or at work. The idea is sound and could be very prosperous. Good luck!
I would think you will need a CC swipe machine and a merchant account because yours is a great idea. Plus, it will help reel in those cash discounts ;-)