I'd go with the 18-135 and expect to use it at the wider end and have fun.
I shoot a lot of cars. I was using the DA 15 mostly because UWAs give the car some swoop, as mentioned above. Also, you will be a bit closer than the cellphones behind you, which is helpful. I used the 21, 12-24 or 40 sometimes, too.
15.
21.
40.
As I no longer have any of that gear, I mostly use a 28mm on full-frame. I also use a 50 which works if there are not too many people in the way, and gives a pleasant perspective. I used to take a macro lens for close ups of details but I find I don't look for those shots much anymore. I used a 17 which seems a bit wide on FF, though can work for some shots.
17 (FF). Porsche club judging held at the Santa Monica air museum.