Talkboard member & Moderator: Information Desk, Alaska Mileage Plan; FlyerTalk Evangelist
Join Date: Mar 2004
Programs: UA G, AA GLD, AS, AGR, HZ PC, Nat'l Exec, Costco Exec, NPS Passport
Dollar typically focuses on having a highly competitive base rate and doesn't participate in a lot of super-duper discount programs. You might be able to knock 5% or so off with a promo code but not much more.
If you can post some details about your trip (where, length of rental, etc.), perhaps some here can provide some assistance...