on site tracks do create a huge draw of people, but only if the rest of the puzzle is there. there was one hobby shop close to me that had the parking lot paved with a special asphalt that was real sticky for an onroad track (it was setup on weekends), an offroad track (it was a tight track for 1/8 scales, perfect for 1/10), a micro track in the basement as well as a slot car track. was quite popular, however if you wernt a part of their "crowd" the guys that ran the shop were quite arrogant, and i only ever saw the same crowd in the shop and on the tracks, i think the attitude of the employees drove the new customers away. i myself never went their much because of it.
having tracks is a great idea, but the rest of the puzzle has to be their as well. as far as test vehicles goes, good idea but the cost of a track is big enough already, having 1 of everything you sell could push the costs right out of proportion. imo, experienced drivers are going to know what they want when it comes to a new vehicle, most do tons of research before they buy and don't really need to drive to compare stock vs stock as they will change a lot anyways. the target here should be rc newbies. have some basic vehicles that you would sell to a newbie, such as an hpi savage, axial ax10, traxxas slash, ect. chances are that if you recommend a rtr kit thats the type of vehicle they are after, and let them drive it, they are going to walk out with it.