Car t-shirts - licensing/trademarks/copyright

[splash gti]

I was wondering about trademark/copyright/licensing issues if designing car T-shirts in an illustrative way - similar to some sold on this site - and am trying to find out more information. The designs would be positive and not derogatory in any way.

Would I have to contact each car manufacturer? Any ideas on costs? What if the model was no longer manufactured?
I've seen brands/models reproduced many times in supermarkets, shops etc and just wondered what path the original artist would have taken. Thanks.

[splash gti]

Thanks to everyone for your replies/input. Lexul, if I go down the screen printing route and it becomes a success then I'll be in touch.

It looks to me as if most sellers/artists are chancing it, because no matter where I look there is infringement/trademark/copyright issues, which is what I initially thought.

I'm going to try a similar method to SDITH, which seems to be working well enough for them - state copyright/trademark owner, say the artwork is inspired by (the company), and that the work is in no way associated with (the company). Thanks to Kozy for making me aware of their terms.

In the meantime, if anyone gains permission/authorisation and would care to share how they do it, please get in touch.