We have two gas qualities (mainly)
Stanfard is 95 research octane, leadfree
premium is 98 RON leadfree
Deduct about 5 octane numbers for US PON (pump octane) gas, for better gas stock qualities, deduct about 3 octane points.
European engines are made for standard EU fuel, which is about 90 PON in the US. That is premium gas! Anything less, and one walks the thin line along the abbys.
We pay about 1.50 euro for a liter standard gas, which is ~6.00 euro/gallon. At current dollar rates, that be $9.00-$10/gallon, give or take a little.
The trip to the field guzzles more money than the plane, so it is no use to use lesser quality gas. Only premium will do, even in engines designed for low octane fuel. They will not run better, but at least the engines designed for premium will not get hurt! Running more octane does not hurt. Running too low octane will destroy your engine in time. To me, this is a no-brainer. Get premium gas whenever you fill up for our toy engines.