The DOT has said customers are not required to sign such agreements.
The groups, however, say shoppers are being pressured into less favorable deals, even if no waiver is signed.
The program allows consumers to trade in old gas guzzlers for up to $4,500 if they buy a new, more fuel-efficient car.
A DOT spokeswoman was not immediately available to comment.
More money-related links:
- Save money with Local Coupons
- Coupon Bug helps you save cash
- Saving with 6abc reports
- Share on the Saving with 6abc Message Board
- Track your stocks
- Follow Action News on Twitter
- Get Action News on your website
- Follow Action News on Facebook
- The latest Philadelphia headlines from the Delaware and Lehigh valleys