PartyHatPete welcome to iRacing and congratulations on your D license. Unless iRacing surprises us with the 2022 season 2 release, there are 3 GT4 Choices, the Porsche 718 Cayman GT4 Clubsport MR, BMW M4 GT4, and McLaren 570S GT4. It's largely personal preference but I think you should focus on either the McLaren or the Porsche. The BMW is not especially loved, it's doesn't want to turn and is prone to both understeering and oversteering. There are people that can drive it quickly after enough practice, but it's not a great starter. There's a BMW D series, but if you want to race in this league you're better off getting your C license to practice in the official IMSA Pilot series. Porsche is the most popular in official races, and I think it has a slight performance advantage this season. The Porsche GT4 can also be used in the Nurburgring endurance races, which is nice. But the McLaren blows fire from it's exhaust, which is awesome.
Robbie_gtc also demolished us a couple seasons ago in the McLaren.
There are a few things to keep in mind with all the GT4 cars
- GT4 tires take a fair bit of time to heat up. It'll feel like you're floating the first couple laps. Give them time then they'll grip up nicely.
- There's enough horsepower to get you in trouble, especially on cold tires.
- The GT3 version of each car doesn't specifically behave like the GT4 equivalent from each brand, so don't let that sway your decision.
I've been sim racing for about a year and half. I worked through the licenses pretty quickly, but the last two seasons I've had the most fun in the Advanced Mazda league. Slower cars tend to have closer racing, and it's easier to learn driving technique at lower speeds.