Don't get decieved by a relatively low score on Metacritic, that's unfortunately a result of reviewers comparing FlatOut to Need For Speed (most popular racing game of mid-2000's). Although they belong to the same main genre, racing, they are completely different games with completely different perception of racing.
I played this game for the first time when it was released in 2005 but I was not able to get pass through the first stage of three as I was not that good in PC games back then. I grew up, saw this game on discount and I was determined to complete this after all those years and finally managed to complete the game in 15 hours.
During 15 hours, I completely lost my s**t, I leaned right or left on my chair while I was simply pressing left and right buttons on my cheap keyboard, I looked for a brake pedal under the desk, I felt like I won a real race after each race. This is probably one of the most underrated games of all times as it's gaming mechanics, AI, graphics are better than current era of arcade racing games.
FlatOut reminded me why I loved racing genre. 10/10.