Vacuums. The one engine-based items that humans DON'T try to race.
Cars. Trucks. Tractors. Helicopters. Boats. Segways. Possibly even a motorized cotton gin. Anything that humans can strap an engine into or on top of can and has been raced... except the humble vacuum.
But don't despair, vacuum enthusiasts. The Hoover WindTunnel Pet Vac has the mobility you'll need on the day that your day finally arrives. Watch as those other, lesser vacuums go flying to the left and right as you take the corners! See them pile up in a sad desperate heap and cry as you burn past them light clean lightning! Thrill as YOUR path to the finish line is the path most free from dirt and dust and clutter!
Or perhaps hang back a little to keep it close? After all, vacuum racing is never going to get big if it's always a blow out finish. One needs a little competition, one does.