I used a code from Sam's Club several months ago (Rate code BY, Associate ID 371630) and had a coupon for $15.00 off - I got a mid-size (Grand Am or similar) unlimited mileage, 1 additional driver for a weekly rate of $146.99, $38.89 taxes & fees, for a total of $170.88
But I have tried that same rate and code recently and it was much higher than the rate I originally got, so I don't know. I've tried several different rates & codes, and different rental companies, and haven't found one close to the rate I've already got.