When I rent a car from USAA using the discount code provided to USAA members, I get some very nice discounts. While the rate reduction is very good, the huge discount comes from the fact my wife is added to the rental at no additional charge. On vacation rentals, that works out to something like $50-90 in savings.
In addition, I was able to sign up for Hertz #1 gold club for free. This saves me $60 per year.