- Broken Base: Despite being very successful, the Underground games ticked off the older NFS fans who didn't buy into its Fast and Furious-inspired tuner culture aesthetics, and the cars' performance becoming divorced from Real Life counterparts with balancing and progression considerations becoming major factors in the cars' abilities.
- Friendly Fandoms: With The Crew for being an open world racing game with car customization much like Underground 2.
- Game-Breaker: Any four wheel drive vehicle. Due to their increased traction and traditionally higher horsepower, they oftentimes get a much better launch than vehicles of other drivetrains. This allows them to gain a considerable advantage in many Street X and Drag races.
- Germans Love David Hasselhoff: NFS: Underground was a huge hit in Brazil, mainly because of night street races and car customization. Almost every PS2 owner in the country owned a copy (pirated or not) of the game. Easily one of the most popular titles during the 2000s along with Winning Eleven/PES, Counter-Strike and Grand Theft Auto: San Andreas. Plus, the game helped foreign black and hip hop/rap singers to became popular in the country, like Snoop Dogg, Fat Joe and others.
- Harsher in Hindsight: The first game's soundtrack contains not one but two songs performed by a sex offender. "The Only" by Static-Xnote and "Ride" by Lostprophetsnote .
- Narm: The plots are flat-out awful, with the fights to be the best illegal street racer in the city being too much Serious Business for its own good.
- Narm Charm: They still have their fans, however.
- Scrappy Mechanic: Star Rating. While in Underground 1 it is only used for some optional unlockables, in order to advance past certain parts in the Career Mode in Underground 2, you have to complete a time trial to reach a spot in the map to have your car published in a magazine. Said car needs to have a minimum Star Rating to be able to take on it, and said Star Rating is increased by applying visual customization to the car. While forcing players to take on something that should not be mandatory in a game genre is already questionable by itself, it does not help that the late-game visual customization options, necessary for the later magazines, make the car look like a very blatant Rice Burner. Thankfully, subsequent games did away with the star rating, making customization (almost in the Most Wanted and Carbon games, where visual customization is necessary, but not arbitrary and mandatory, to reduce the cop heat attracted) completely optional.
- Sequel Displacement: These games were so popular that many gamers who grew up with these games (alongside Most Wanted  and sometimes Carbon) see them today as "classic" Need for Speed, even though there were six previous NFS installments released before Underground came to the scene.
- Special Effect Failure: The prologue of Underground 2 showcase the player racing around Olympic City before moving to Bayview is obviously shot around Bayview.
- Spiritual Licensee: These games were this to The Fast and the Furious for sure.
- That One Level:
- Drag racing. It's often viewed as needlessly-overcomplicated.
- Event #95, Kurt's Killer Ride, in the first Underground. It's important to know that this event takes place in the final stages of the game, where the player should already have a maxed-out vehicle. Because of that reason, the rubberband AI has a stronger effect on opponent cars. This combined with the fact that the race is a six-lap circuit in a technical track makes Kurt's Killer Ride a very difficult race.
- They Changed It, Now It Sucks!: Most of those who started playing NFS before Underground were disappointed by the extreme changes given by that game. For some, the franchise died in the Underground era.
YMMV / Need for Speed: Underground