Believe it or not, motorsport coverage is very weak in the UK. We regularly get F1 and British Touring Cars. I find both boring and massively watered down. I'll have a look into WTCC on the cable channels though, thanks for that.
EDIT: The hey day of car racing in the UK was in the 80's with Group B (all forms: rally, touring car etc), Turbo F1 and Group C World Sports Cars. F1 calmed down when Mansell left F1 (funnily enough, Indy Kart became very popular when he moved to that series). Most other sports that were broadcast died out very quickly after the demise of Group B/C. Bikes took over then with GP500 (now the formula has changed to Moto GP) and Superbikes. Even MotoX had a following but that's gone too!
Off-topic but I had to reply.
Sorry but this is utter nonsense. Right now I have more motorsport stacking up on my Tivo box that I can realistically watch, you just have to look outside of the main five channels.
Touring cars from around the world (BTCC, WTCC, Aussie V8, DTM and more), open wheel (F1, more formula stuff than you can count), Rally (WRC, FIA ERC, European Rallycross, Rally Raid, Dakar, Androis Ice), Sportscar and Endurance (Le Mans, ALMAS, Blancpain Endurance, etc) and well you get the idea.
Not only has their never been more motorsport on British TV (and I've been watching it since the '70's), but the duration of the coverage is far, far better than ever. You can watch every race of the BTCC (rather than highlights), all 24 hours of Le Mans and N24, every race from the V8 Supercars.
You may not have found it yet, but that most certainly doesn't mean its not on.