10% ethanol blend will only damage most vehicles with extended use (meaning 80,000 miles or more). I don't really know what would happen with older (meaning 20 years or more) cars though or cars that have really high milages already. It doesn't get quite as good a gas milage as regular gas. Besides the premium fuel I use in the Mercedes (91 octane or higher) not being available in a low ethanol blend, I typically pay the extra amount at the pump for the stuff without ethanol for my truck. Lately this hasn't been a problem with the price of ethanol rising.