Are there any vehicles in video games that you really like, regardless of whether it's something you modified/customized yourself, something driven by another character, or a fixed design (such as every vehicle from the first two Midnight Club games)?

For me, the coolest pre-designed cars I've seen in video games are the ones driven by the 15 Blacklist racers in the original (2005) Need for Speed: Most Wanted:

#15: Sonny, Volkswagen Golf GTI (Mk5)
#14: Taz, Lexus IS 300
#13: Vic, Toyota Supra SZ-R (Mk4)
#12: Izzy, Mazda RX-8
#11: Big Lou, Mitsubishi Eclipse GT (4G)
#10: Baron, Porsche Cayman S
#9: Earl, Mitsubishi Lancer Evolution VIII GSR
#8: Jewels, '05 Ford Mustang GT
#7: Kamikaze, Mercedes-Benz CLK 500
#6: Ming, Lamborghini Gallardo
#5: Webster, Chevrolet Corvette C6
#4: JV, '03 Dodge Viper SRT10
#3: Ronnie, Aston Martin DB9
#2: Bull, Mercedes-Benz SLR McLaren
#1: Razor, BMW M3 GTR (Race)

Personally, I like the unique livery on the car of #7 the most, but for overall appearance, #1 wins that.

As for cars that I customized myself? In Need for Speed ProStreet, I own a turbocharged and heavily modified Nissan 350Z for Drift races; I really like the livery I made for it because of the large, angled vinyl on both doors that appropriately reads DRiFT INFANTRY. I'd normally include a picture of the car, but I don't have one ...

Well, there has been a few Dukes of Hazzard games, and I'm pretty sure there was a Speed Racer game, but even then, I tend to recreate both the General Lee and the Mach 5 in Need for Speed and Forward. And there was that time on Forza Horizon 2 I made a Herbie and the Mystery Machine.

i really like Ray Carter's Ventura from FlatOut 2 & FlatOut UC

but cars ive customized I had this Full White 2010 Camaro in The Crew unfortunately i dont have a pic of my car