I asked a friend in the Cadillac dealership:
Research the area and dealers that are of interest to you.
Developed targeted resumes for each dealer.
Include a letter of reference from previous employer and statistical information on the last 3 years of sales. Your marketing, sales skills and techniques need to be emphasized. If you can, get references from district managers.
Awards
Achievements
Education
Certification from auto maker
Bring a disk with internet website for sample work
Better yet, have your previous boss network with the dealers (new trend due to the number of folks seeking employment). Some owners prefer if the previous employer will contact them and start the process. Normally this does not happen often, but render superior results...

Hope this helps...