This is a form of racing originally developed by a PS3 racer named Enzo_Guy on Midnight Club LA. It is fast-paced checkpoint style racing with large amounts of intersecting and crisscrossing segments, but almost no straight sections.
Creators of highway onramp races use race editor to design races in an area where multiple highways merge to utilize the most onramps possible. The basic setup is to place a checkpoint on one onramp and then to place the next one on a separate onramp, forcing racers to rip hard u-turns and creating tight hairpins. The race creators aim to design the tightest corners and most collisions possible. Designers only have a limited number of onramps, so participants are often going different directions on the same onramp which invariably leads to lots of head-on collisions
City onramp racing features extremely tight corners through parking garages, alleys, and even inside buildings. Whereas highway races focus more on causing collisions, city races focus more on causing confusion. Race creators often start city races with the participants facing a wall. Race creators usually get lost on their own tracks.
Almost any car is suitable. A driver, instead of using his fastest exotic car like most other races on this game, will pick a vehicle that best suits his style of handling hairpins and u-turns. One racer is known for being competitive in a Golf GTI
Quotes of onramp racers:
"It doesn't matter what place you come in, this is the most fun you'll ever have racing."- a racer describing onramp racing
"I'm in a Gallardo! How is that Golf beating me? Fuck that Golf!"- a racer participating in an onramp for the first time
"I missed the turn!"- a common exclamation yelled during onramp racing
"It's like autocross met destruction derby."- a racer describing onramp racing
"How the hell do I get up there?"- a common question shouted by racers
"Dude, this shit had to have been designed by stoners who forgot to take their ADD meds."- a racer's opinion of how the track looked on the map
"This isn't racing, this is bumper cars!"- a racer describing a particularly perilous city track