We provide the service for dealers free if they have a car for us to return in(exchange). If it's a blind trip that we charge $10. We have a fleet of drivers on the road, all retired car salesmen. They love it, we pay them $5 per car. To come to the shop in the morning they use a retail customers car(they pick it up at the customers house, leave there car there, reverse scenario at end of day).
Being retired car salemen, they have credibility when they go to the dealers, and get paid a commission on up sells, so they do a good pre inspection. They aklso do teh post inspection before leaving the shop.
Like Scott said please make sure you have the proper insurance coverage for this before thinking of driving a customers car on the road.