IRL street racing falls into three catagories.
1. Mindless twerps who see another hot car at a stop light and race right then and there amidst traffic.
2. Organized street racing groups.
3. Amature racers of street cars on legal race tracks.
The Mindless twerps will race anywhere. There's no money in it, only pride. The light turns green-both cars take off, whever first gains a lead is the winner. Generally no words are exchanged. After the race they drive off in seperate directions without ever speaking or knowing each other's name.
The organized street racing groups are slightly better. They tent to organize a meet (generally in a shopping center parking lot). The meet is more for checking out cars and so forth. Challenges will be made at the meet and the group will then gather at a set time in a set location for the race (or generally races).
Organized street racing groups tend to favor warehouse districts. If you check urban warehouse districts for a bit you can usually find a nice stretch of straight, flat roadway uniterrupted by any intersections that is wide enough to race two cars on and is surrounded by warehouses with minimal staff at night.
The organized street races tend to have a lot of spectators (often as many as 100 cars). This is where score is kept and money changes hands (though IRL it's more along the lines of highschool and college-aged kids, so bets are not high stakes like in the movies). Frequently the only prize in a race is pride and bragging rights within the community.
Gang participation IRL seems to be minimal (no real profit except for the winning racer- no way to sell tickets or entry fees- if people wanted to pay tickets or entry fees they'd go to the race track). Organized crime does sometimes fund street racer groups in order to keep the street cops busy, but not as a means to turn a profit.
The three catagories tend to overlap each other heavily. Some members (I use that term loosely, there is not formal membership) will participate in all three forms of racing (twerp, organized street race and race track), others will participate in only one or two forms, and still others are around just because they like cars, but don't actually race.
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