Here are some tips Pork Pie PMed to me awhile back. I think tip #1 is probably one of the most important.
some information's from long time and experience rental cars in SLC.
1. Don't wear or got something on your luggage which shows that you like to go to the salt.
2. Latest, when you arrive in Wendover, do one thing....get this solid garden garbage plastic bags - cover with this the driver and passenger side floor - fix it with duck tape to the anterior, use small fridge bags, take them over brake and gas pedal and fix them with duck tape.
Covering the floor I found iout - best is - get the carpet out, stuck them into a bag, get them back on the floor - add a second bag on top and fix it with the tape to the plastic parts.
3. Before you leave Wendover - get the plastic bag off - behind Smiths (supermarket) on the the west end of Wendover is a car wash, clean the car, especially under the car, in the wheel arches and in the rear bumper - also on the top of the exhaust.
When you got the car washed - on the way back into town, about 300 yards after Wendover Will on the right side is a big gravel truck parking lot, drive on this and drive a lot of donats, both direction...so you cover the car with a thin dust cloud....
When you return the car, the same as when you picked them up...nothing which can show that you was at the salt..
By the way, at Smiths you get everything you need - before you pay your first bill there, ask for the Smiths discount card - you will get them as a racers friend - no charge - but will saves a lot of money, especially for drinks - like water and coke....also a very cheap place for ice.
See you at the salt
Pork Pie