This is actually the only site I post on regularly, But browse a few others.

Probably biggest car forum in Europe?
Pistonheads.co.uk

UK Drifting Forum:
driftworks.com

Irish Drifting Forum:
driftireland.com

All sorts of random/cool cars:
Retrorides.proboards.com

Biggest UK Ford forum:
Passionford.com

UK site for E36s,
e36coupe.com


Also read a few smaller site like Transitowners forum etc..