Sounds like they're running an insim on their server. As on cruise servers, some of them has a requirement to use car restrictions.
All you do:
Go shift+p when you're on the server > choose the car you want > choose the set >
Under the INFO tab when you're still in garage, you can set the restrictions. Set mass and air restriction to 14% and then it should work. Hope this helps!
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As I'm not home, I can't provide any screenshots.
Yes, I will be doing a giveaway in a couple of days. This upcoming friday actually (10.03.2017).
Its open for everyone:
DEMO -> S1
S1 -> S2
S2 -> S3
S3 -> S4?!