Well, I for one like the Vauxhall VX220 (AKA the Opel Speedster). It was on the box cover of cult classic Metropolis Street Racer and indeed was a potent car in that game. It's a nice slice of British turn-of-the-millennium cool.
This was available for purchase individually, but it made no sense to do so as it was included with all the other DLC in the Ultimate Edition. Forza Horizon 4 isn't generally the kind of game where you absolutely must have a certain car, but the DLC was/is nice to have.