the site is http://www.velocity.com/tv-shows/car-fix/custom-car-sweeps.htm
in the details of the rules it points out that you can enter once a day, and only if you are a resident of the lower 48
The Sweepstakes begins at 12:01 AM Eastern Time ("ET") on January 12, 2014 and ends 11:59 ET on August 31, 2014.
Complete the online entry form and submit so that it is received by Sponsor's server by 11:59 PM ET on August 31, 2014.
Limit one entry per person/email address per day.Note that by entering this Sweepstakes, you are agreeing to receive special updates regarding Discovery programming, events and promotions and to be bound by these Official Rules and the final decision of the Sponsor and Promotion Administrator.
One (1) Grand Prize: A redesigned 1971 Chevrolet Camaro Muscle Car ("Vehicle Prize"), a trip for two people to Las Vegas, NV, for SEMA 2014 ("Travel Prize"), and a cash award of $30,000 ("Cash Prize").
The Cash Prize will be awarded in the form of a check in U.S. currency made payable to the Vehicle Prize winner. The purpose of the cash award is to provide the winner with funds that he/she may apply toward the payment of any tax liabilities he/she may incur as a result of winning the Vehicle Prize, or for any other purpose he/she wishes.