The best smell in my opinion for anything with wheels and an interior is the smell of ozone. Ozone deodorizes an interior and leaves behind the smell of fresh rain. You can buy an ozone generator pretty cheap off ebay for $100 bucks or less and it doesn't require anything but 110V to run it. Very little maintenance.
Important to know though, ozone replaces oxygen in the air, so it must be used empty and aired out, or bad things will happen if you decide to run it while occupied.
If you don't like my opinion, I'll give you a full refund on what you paid me for it.