Quite surprising this hasn't been mentioned here before. Yes, it's an evolution of Game Stock Car and Stock Car Extreme. Yes, it's based on the old gMotor engine. No, there's no rain and no pretty DX11 graphics.
However, the in-house developed content rivals any hardcore racing simulation out there - often coming out on top. Being gMotor-based, there are plenty of community tracks and cars available, the AI is good, there are weekly hot lap challenges, the audio design ensures you don't want to stop treating your eardrums with the scream of a V12 and finally, racedepartment.com organizes club races where you can trade paint with other rookies, enthusiasts, aliens and humans a number of times a week.
It should be noted though that Reiza is finalizing the development of AMS, with their new project codenamed 'Reiza 17' under works currently as well, so this likely isn't a sim that will get future updates for years to come. Also, there isn't a big difference in the content between Game Stock Car / Stock Car Extreme and Automobilista, so if you own either of the former ones already, think before you buy. Still, depending on where you stand, it might be worth a purchase immediately or perhaps for a few bucks less during the summer sale. AMS is sold on Steam.
Now to the real beef, which is the F1 content in the sim. Made a quick recap of it in the form of a video. Headphones recommended, ignore the occasional gearbox grinding sound, that's just my woeful driving.