I'm in HO and I swear by my CMX car. I think they also make them in N scale. The car is a heavy brass tank that can be filled with cleaning fluid. They recommend either isopropyl alcohol or lacquer thinner, with the preference to the thinner. I've tried both, and I agree that the lacquer thinner does a far better job. The car has a needle valve to adjust drip rate of the fluid on to a cloth pad, with rubs along the track.
I just did mine tonight, because I noticed some sluggish behavior which always says, "Clean me!" We're having some guests for dinner tomorrow night, and I wanted the trains to be running well anyway.
I have a layer of subways below my "conventional" layout. Cleaning track by hand would be awkward and time-consuming. This unit is far better.