demensions can be found in the factory crx service manual. You can download it here:
http://www.hondacrx.co.uk/
As far as what stands out for drag cars... either well setup cars or fast cars. I'm very impressed usually when i see an engine bay that is clean and well layed out. The NHRA here usually gives out a "best engineered" trouphy at every race and that's what impresses me the most.
Another thing you could do is lineup a race with a car that people expect to be faster. When a CRX takes down a Mustang that pulls the front wheels around here, people take notice.
In general though, a great way to get sponsors is just to WIN. If you don't get offers, send letters stating your accomplishments to companies and if he's doing well racing and has good times he should have no problem picking up a few sponsors. There is also contingency sponsorships but i'm not sure how they apply over there or even if they exist.