You can also start races by pressing A as you drive over their starting line. The person who issued the challenge chooses any event they have unlocked (there are nearly 200 different events with more in DLC already confirmed), when it pops up it shows the proposed event in the bottom corner of your screen and you can press Back to ignore it, or A to accept their challenge. There can be around 50-100 cars spread all around each server's map at once, and up to eight at a time can jump into an instanced race, cop chase, or other type of challenge. You can start races with any cars around you by pressing A to flash your lights which shows your challenge on every player's screen that is close to you.
Once you get together with all your friends, get ready for hours upon hours of driving around together. There are some other minor problems mainly related to interface and things like finding other players during online play (filtering the map to show only my friends inexplicably showed nobody but I had 4 friends sitting right beside me at the time). This is an extremely fun game with a massive open world, but it definitely has its fair share of issues regarding certain things like the This is an extremely fun game with a massive open world, but it definitely has its fair share of issues regarding certain things like the occasional texture pop-in and/or screen tearing that may occur (which is quite common in open-world driving games).
