I really would like to see a complete map of the island, not just dealerships but all rental shops, estate agents etc.
None of the challenges in the game are really that hard, if you can't reach a particular time, try a different car. Worked for me msot of the time. I think I know the one you're talking about though, a class D one right? yup definitely try a different car. Same for Tantalus (noble m400 for me).