Most slot cars will run on Scalextric track ( not all, particularly Micro Scalextric as the brushes are too widely spaced!! daft or what?) I even had a pair of "Granny Racers" going round a couple of yrs ago!! However, there are a few possible minor pitfalls.
1. Many of these type of car have headlamps, with a non replaceable bulb, and the 14v transformer of a scalextric set will blow this bulb in quick time at full throttle, There is a complicated answer, well 2 or 3, but not worth going into here. generally just accept that bulbs will blow unless you drive carefully. The lights are really bright!!!
2 The guide pin may be too Long and foul the bottom of the slot
3 The guide pin may be too Fat and stick in the slot, either slowing, or even stopping, the car......
.......... the answer to 2 and 3 is simple, just get your wife/daughters newest and best nail file, and file either the bottom, or sides, or both, of the pin........ Simples
Lots of cheap fun can be had with these cars, they go really fast, (remember some were meant to run on a set of D cell batteries) most have some magnatraction too so corner well, and most important they do not damage easily, and if they do.......... well, it's not like crashing your newest fine scale Scalextric car and breaking off the spoiler, or worse, is it?