New Poll -- Your Fav Radio Station
It looks like you have a product that users will vouch for, do you really think that your customer can be reached by the broad brush spread by radio? Radio is a tough medium to tackle for your kind of business. Radio and TV are super expensive - unless you can find a regional motorsports show to buy. If you buy radio be very selective of the shows you buy to be sure they are within your target customer.
Utilize your existing customer base to help spread the word, use online internet forums, online magazines, create a color flyer and distribute them at local car shows where your potential customers would be looking for your company services. Rent a booth, put up an Easy-up at a few car large regional car shows to gauge the reaction to your product and offer show specials.
The cost of Radio is much better spent targeted more directly, radio will be heard by your family and friends and probably miss your potential customer.
I spent thirty years in TV and Radio commercials, there are better, less expensive and more direct ways to get your word out!
Good luck!