Unpopular opinions? I've got a few.
1. Most 1980-1990s Japanese cars look better standard than they do modified, and cars like the Z32-gen 300ZX, Skyline R32 GT-R, and Mazda RX-7 (FD3S) are the first cars I think of here.
2. The "Gulf" livery is extremely overused and honestly looks pretty mediocre, if not outright bad, on most modern cars. Not necessarily all of them, and a few do look good while sporting it (the McLaren P1 comes to mind, and now that I think about it, the 911 GT3-R GPX looks quite good in its colors), but definitely a good chunk of them. It looks best on a Mark I GT40 or a 917K.
3. Many Porsche purists I know seem to hate the Porsche 996, but I quite like it. The fried-egg headlights have actually grown on me, as time went on.
4. The hate for the Mark V Supra is way, way, WAY overblown. It's not THAT bad of a car. Hell, it's not really a "bad" car at all, but people throw it in the garbage without giving it a chance for not being a literal carbon-copy of the Mark IV. It's pretty sad, in hindsight. The older Supras had little to nothing to really call them comparable to one another, except being RWD, 2-door, Inline-6 Sports Coupes, and the Mark V ticks all of those boxes. Its B58 has even proven to handles 1,000+ HP, but nah, people still barely bat an eye. Whatever floats their boat, I guess.