What I did was a little diffierent. I took a piece of masonite and cut two grooves in the rough side that are the same spacing as track. I put this in a shallow aluminum foil contaner and added alcohol to just cover the board. Grab a car, run it through the grooves for a few seconds, and set it on a paper towel (to absorb the excess alcohol), and grab the next car. The rough surface of the masonite helps to scrub the wheels. With the solid surface around the grooves, the car easily slides into the groove for cleaning.
A word of caution (actually, several). Use in a well ventilated area. With that much surface area, the alcohol evaporates quickly. Also, if you paint your wheels and trucks, test on an old set first. The alcohol may take the paint off.
If anyone is interested, I can post a picture.
Tom