I guess because it uses gasoline, and that requires a very tightly controlled homogenous mixture, and a narrow temperature range to be maintained. I don't think a fuel with ether in it would work well for every day auto use, nor make the EPA very happy as it vaporized away.

On this subject somewhat, I have a race boat with a big block Chevy with 13:1 compression. I normally run it on Avgas. One day I wanted to fire it up for a few minutes but didn't have, and couldn't get Avgas for it. So I fired it up on auto fuel. It wouldn't turn off!!! It just sat there running and pinging and knocking until I could frantically get the fuel supply shut off and the carbs finally ran dry.

AV8TOR