What you are being offered is not a "sponsorship". You are being offered a parts discount.
My car is sponsored by the following companies:
Crutchfield
K&N
American Sportscar Design
Dynamat
Eibach
KYB
I also have discounts available to me locally by Bap Geon Auto Parts and Creative Concepts and Design (who is responsible for all of my body work and at least three different House of Kolor paint jobs).
(So, I'm not trying to be a ***** here, but define "reputable" because as far as I know, those are pretty reputable!)
In my opinion, you have to already be doing something in the auto scene in order for a company to consider you for sponsorship. For example, compete actively and place well in auto competitions.
2004 MECA Virginia State Finals SPL PHAT Car Award
2003 MECA Maryland State Champion SPL CS4 Class
Once you get your vehicle seen and get awards (which typically involves dumping quite a bit of cash into your ride FIRST), then you might get an offer. The offer may include product sponsorship, travel expenses for shows, etc.
My sponsorships are ongoing, and I am often called upon to show my car someplace at a vendor booth. You may have to be prepared to do things now but potentially years down the road depending on the terms of your contract. My advice to you is to make sure you have your attorney read over whatever contracts you may get. I have been very happy with mine, with no complaints, though I do miss Rex Orr from ASCD since his death last year.
Note: Keep in mind that there are very few sponsorships going on in the industry right now. NOPI even cancelled their season, which was bigtime into sponsorships...So, don't be discouraged.