As with model rockets, a lot has improved in slot cars since the last time around: high-energy ceramic motor magnets, silicone rear tires, independent front wheel rotation, light-weight polymer traction magnets, separate power supplies for four racing lanes, banked turns, and, of all things, brakes.
To get back into the hobby as a GeekDad, I recommend the AFX Super International boxed set, with the 4-Way Split as a second choice as it has notably worse cars. To the base kit, you can add banked turns (my favorite), chicanes, split track, and lap counters.
The aftermarket cars have very different performance levels. “Top Dog” in this photo is the Super G2 from BSRT, and it can go so fast that it’s hard to see… but it can also fly off the track with dramatic effect in a tight turn. (The G2 is better than the G3 IMHO)
(From HO Speed Tips)
A stronger traction magnet can help with cornering, but will lower the top speed (it’s like having more friction to work against). With a standard AFX power supply (even hotwired as I have done to avoid sharing power supplies across lanes), the Wizzard’s magnets are so strong that they never leave the track, at full throttle in the tightest turns (red and blue Lexan bodies above). So that’s OK for the kids to learn with, but not so challenging.
But… with an aftermarket power supply and a custom-built single piece track, they can be “in balance” again. My racing buddy has just that. His track is designed to fit a specific space in his house, and the entire 4-lane track loop is one huge solid piece. I have no idea how they installed it. As with any hobby appealing to big boys, the cost can go exponential.
Four parallel lanes with various turn radii is a kick. It also has a built in digital timer for each lane, to compound the competitive pressure. The dynamics of guys practicing solo racing vs. four-person competitions follows the Sapolsky rule for baboons:
“When baboons hunt together they’d love to get as much meat as possible, but they’re not very good at it. The baboon is a much more successful hunter when he hunts by himself than when he hunts in a group because they screw up every time they’re in a group. Say three of them are running as fast as possible after a gazelle, and they’re gaining on it, and they’re deadly. But something goes on in one of their minds—I’m anthropomorphizing here—and he says to himself, "What am I doing here? I have no idea whatsoever, but I’m running as fast as possible, and this guy is running as fast as possible right behind me… I’d better just stop and slash him in the face before he gets me." The baboon suddenly stops and turns around, and they go rolling over each other like Keystone cops and the gazelle is long gone because the baboons just became disinhibited. They get crazed around each other at every juncture.” (from EDGE.org)
I jokingly call the timed slot car races "baboon races" as over-eager cars inevitably fly off the track in the very first turn…