1: VW I.D. R
Now I understand this car didn't race in any series, but if this isn't a race car then what is it? The I.D. R first came about in 2018 and set a new outright record at the pikes peak hillclimb. Not just for EVs, all cars. 2019 was another great year for VWs crazy "thing". After their success, the guys in Germany decided to look for a challenge closer to home. Obviously, it was the Nurburgring. This time VW were targeting the EV record around the fearsome Nordschleife. And they absolutely smashed it with a time of 6:05.336. Not bad for something that sounds like kettle.
2: Mercedes AMG W10
This car was always going to appear on this list. The W10 was Mercedes most dominant car since the 2014 Merc. Throughout the 2019 season, the W10 gave Mercedes 8 1-2 finishes and secured both the constructors' and drivers' championships. Boring may it be, but this car showed how good Mercedes is as a team in terms of designing an extremely competitive car and making it count on race day.
3: BMW 330i M Sport BTCC
Now were getting onto the good stuff, the BMW 330i M Sport was pretty dominant throughout the 2019 BTCC season. In fact, only the Hondas and a couple of other cars could even come close. It wasn't just the awesome performance that made this car cool, it was the quick build time. The green light for the project was given on the 1st of October 2018 and the car had to be ready for the BTCC media day on the 27th of March. WSR rose to the challenge and had the car ready by the deadline. Oh, they also won a drivers' championship with it. As you do. Imagine asking the Mercedes F1 team to start designing their car in October. They tell you to go away, but only in a more fruity way.
4: McLaren MCL34
This one is more of a personal choice. As a McLaren fan, it was difficult to watch the team struggle during the Honda years. Most of it was their own doing, but that's for another time. So when 2018 came around and McLaren had ditched the Japanese engines in favour of the Renault, everyone thought they would be ruling the midfield. Unfortunately, that wasn't the case and they didn't do quite as well as they hoped. A large amount of restructuring took place within the team for the 2019 season and the MCL34 was produced. This car was much better than the MCL33 that proceeded it and the results showed. McLaren took 4th in the constructors' championship (the top of the midfield) and achieved a podium finish at the Brazilian GP. The MCL34 brought McLaren out of their rut, and that's why it's one of my favourite race cars of 2019.