It really depends on how many mice there are, and how desperate they are. The smelly stuff and the electronic noise makers make a location less pleasant to the mouse, but if it's still the best site available the mouse will still nest there.
If you have a TT, the best thing to do it completely seal all possible openings - usually places where pipes, gas lines, and electrical penetrate the floor (sometimes hidden behind false panels, under the tub, etc....).
If you have a motorized vehicle, it's really not possible to seal it completely. I use the smelly stuff and noise makers in my minivan and they help some, but I still find mouse nests and still have to replace the cabin air filter every spring.