Surprised you're seeing lower rates on Hertz.com most of the time. It probably depends on what the default CDP is on your profile. When you book at Delta.com, they apply the Hertz CDP for Delta. In this case, it was probably lower than whatever got applied from your profile.

Worth mentioning here, that if you check rates via AutoSlash we check not one CDP, but all the ones you are eligible for based on information you provide to us. The more discounts that can be checked, the lower your rate, so probably worth comparing. You can also apply your Hertz Gold Rewards number on the checkout page to earn points, skip the counter, etc.