Concerning using fuel containing alcohol in the Coupe . . . Besides what John said, gasohol can be lots worse than simple mogas in stripping any sloshing compound (or even regular dirt) from tanks and hoses and clogging up things that ought not get clogged.
Also, the alcohol can degrade things that are impervious to avgas and even mogas. Can you guarantee the insides of your fuel lines are impervious to alcohol? How about the varnish on the fuel gauge corks? The diaphragm in the fuel pump? How about anything that's not metal? NOT recommended unless you can, somehow, overcome these issues as well as the legal ones. Ed
