How I wish I had some photos of some of my models. Back inthe early 70s at the Eastern cruisers monthly evening socials at Cottons Park, we occasionally used to set up a slot track, (bigger than scalextric) and various members would bring along rods and rails to race. The power pick ups were generally on a hinged arm mounted at the mid or rear of the chassis so that the power could be kept on through any wheelys.
I only built four, my favourite being a dragster with an open rails chassis made from brazing rod, two electric motors joined together but disguised by blowers and rockercovers surplus from those 3 in 1 kits that were around then, and slicks cut from high density foam plus a piece of card for the body panels. It looked the biz and worked well.
As things moved on folks started building ever more sophisticated models, perhaps the ultimate being several model aero engined nitro burning fliptop wagons, using half wave rectification through the slot track to control throttle and a clutch; these were probably about 1/12 scale; initially we tried to run them in the clubhouse and it was entertaining watching people stumbling out of the door as the nitro fumes got to them. So the track was extended and had to be setup in the car park to run them. Alan Stevens (who later built the V6 Snoopy Minor van) was one of the builders. That all came to a halt after one of them went off the end, at full tilt, destoying itself and damaging other(full sized)vehicles in the process!!