If I'm solo I just take a red plate route taxi and pay the rate but round up as a tip and to avoid change.
When it's Donna and me and one of our regulars isn't available I offer twice the route rate pp, again rounding up plus more for waiting or jumping the route. Like Treehouse to Three dives. Almost never had to haggle just move on. In either case if we click I get a card or number. You can never have too many reliable friends that drive!