Another-long-post-time! lol
Now, while I have played a lot of the Saturn Racers above, I've probably spent 3x more time on the DC than I have the Saturn, thus these games, I have intimate knowledge of all aspects of them.
Tokyo Xtreme Racer: Worth it for 2 player (if you game with someone else) and to experience, "floaty physics." (It's actually fun). But massively-pales in comparison to its sequel, in every which way, otherwise. Still worth a pick up.
Suzuki Alstare Racing: A motorcycle racer and a decent one at that; nothing groundbreaking, but fun is to be had and while it is a touch easy, there's a lot to do.
Test Drive 6: Only really worth it for the Police Chase mode and the fact that Cars by Gary Numan plays constantly lol
Test Drive Le Mans: Arguably a top-3 racing title on the console; it plays fantastically, it looks superb and so many modes! You can even drive the 24 hour mode, it is an exceptional title.
Speed Devils: A wonderfully-fun little title this is, it doesn't look too great and the laps are LONG (which I like; most people don't though, apparently), but there is so much to see and do and there is a great amount of longevity to this title, especially with all of the different aspects and permutations to each and every race.
Speed Devils: Online Racing: Had this title for years, thinking it was Online-only, but it isn't! Basically a semi-sequel to the above, it's the only game on this list I need to play more of.
Sega Rally 2: As I wrote above, it isn't a bad game at all, but it is lacking to an extent. If you can find it cheap, absolutely worth a pickup.
Sega GT: This is a terribly-fun title and there is customization after customization that is able to be done, featuring dozens and dozens of real-world cars and you can even create a bunch of your own vehicles, from scratch. The only issue (as Xat mentioned) would be that at the higher vehicle levels control a bit, too-realistically; you need to get the feeling downpat and it is difficult.
Hydro Thunder: A boat-racing game by Midway and it is actually very good; think of it as a poor man's Rush 2049 (which I'll get to below), on water. Turbo boosts, different boats to select from, good track design, well-worth a pickup (IE: ensure that if you do, it is the batch of copies that say, "Hot! New!" as the first run had problems).
Wacky Races: Based off of the Hanna Barbera cartoon, this is a
very well-made racing game and at first, you'd think it to be just a cartoony bunch of nonsense. There is a ton of depth and a lot to do, race-wise (jumps, secret shortcuts, items, etc.). Pricey and a bit hard to find, however.
Ferrari F355: Passione Rossa: Yu's game and a phenomenal title at that; super realistic and superb graphics with detailed car views (the arcade cabinet had 3 screens and was something like $25,000 USD when it came out). a difficult racer, but there is a lot of fun to be had and the home port is very deep.
Daytona USA: I still prefer the original, given that I've spent hundreds of hours on the Saturn version and another hundred or so in the arcade, but this is a super-enhanced port, with a ton of extras, new tracks and music. Great title.
F1 World Grand Prix II: Have never played the first title, but this is much better and a solid game from top to bottom, from what I've read, the best F1 game on the console. I can confirm that is superb.
Flag to Flag: The game gets unfairly-bashed on the internet, but I think it has more to do with it being an Indy game, as opposed to F1; it isn't bad in the slightest, but it isn't the best title on the console either. If cheap, well-worth a pickup.
Rush Rush Rally Racing: An indie game from... 2012, I think? It is a top-down racer ala Micro Machines for the Genesis, but much more intuitive, better-looking and fun. Quite a bit of depth to this one too, despite it looking like it does.
Surf Rocket Racers: A Seadoo-based racer and not half bad; another one I need to play a bit more to fully-experience.
Trickstyle: a... hoverboard-based racer? Yes indeed. It's hard, it looks decent, it plays mediocre. It's worth a pickup, but it's far from one of the best titles of this list; just a hair above average
And, IMO (basically the consensus), the 3 best racers on the console:
San Francisco Rush: 2049: What a phenomenal game. The N64 version is mediocre, the arcade version is superb, but the DC version blows both out of the water and has the same functionality as the arcade version did. An arcade racer through and through, it does have a few extra modes, in the Stunt and Battle modes, along with an excellent obstacle course. Completing this game fully (collecting all coins, completing all circuits and races with top times and beating everything fully) took me almost 1 1/2 years of fairly-consistent playing. So worth it.
Metropolis Street Racer: The spiritual predecessor to Project Gotham, this game is fantastic from top to bottom. More sim than arcade-style, but a hybrid of the two styles of racing games, it has a unique scoring system called the kudos system, which rewards good and stylized-driving, while punishing accidents and slow, poor driving. There are 20, "chapters," to complete, with 10 challenges in each and this game will also take you a LONG time to beat (I believe it was 4-5 months of playing basically every day). Also has remarkably-crafted (and accurate) locations, as well as dozens of tracks of unique music, that attempt to mimic real-life musicians (Let's Get it on Tonight! XD).
Tokyo Xtreme Racer 2: It ditched the 2 player mode, got rid of the floaty physics and added... A TON of cars and parts, not to mention 9x the amount of road to drive on, that the first had (at least I remember reading that it was 9x; may be less lol). The best sim on the console by far and, like the other 2 games in the top 3, this took me months to beat and more months to fully complete (the Wanderer requirements; want to pull your hair out sometimes!). it is just so much fun and so well-made, it is my #1 favourite racing game ever and, IMO, the best racer on the console.
I have stayed away from the, "notorious bad games," like Roadsters, MagForce, TNN Hardcore Heat, Spirit of Speed, etc., so I don't know if these are good games that got a bad rap or if they really do just suck (I know Spirit of Speed is absolutely horrifically-bad, easily one of the 3 worst Dreamcast games in any genre, if not the worst).
There are also a few decent ones that I have no interest in, like Vanishing Point, Looney Tunes Space Race, Star Wars Demolition Racer and a few others, that may be worthwhile.
Then there are a few titles like Pen Pen Tricelon and Re-Volt that I would be interested in giving a whirl, but just never have picked up (have played demos of both and they are fun).
Something a bit different:
Super Runabout: San Francisco Edition: A, "Driving Mission," game, as opposed to an all-out racer, you need to complete goals and conditions to progress. Actually a lot of fun and a decent game, another I need to spend a bit more time on
Crazy Taxis 1 & 2: While technically not, "racing," games you do drive around and they are AWESOME titles; 2 is the better title, but 1 is definitely my more-preferred (same with the fans, though the first was released multiplatform and 2 was DC-only). They are expensive, but they are up there among the Sega greats.
Toy Commander: Planes, tanks, trucks, cars, lots of driving to do, including some races! A tricky game, but once the controls are downpat, you will have a blast. Also had a racing-only sequel of sorts, called
Toy Racer come out, just in PAL territories, but people bashed the shit out of it (having not played it, I have no clue why).
Vigilante 8: 2nd Offense: A ton of fun, but it does look a bit rough and some vehicles control poorly (that was the point, but I digress). It is vehicular combat, so driving around, shooting other vehicles, picking up powerups and completing missions.
If you want to see some vids, I did hour gameplays (basically) of the majority of titles that I have included here, back in 2015:
I can't post the actual links here at work, but just go to videos, scroll down to January 2015 and you'll see the vids.
Sorry for the essay!
