About $10 a gallon. So, $90+ an hour just for gas in the 172. Better than not flying at all, but getting to be very expensive. Some of the cost might be mitigated by longer engine service life but I doubt it will balance out.
As Fast-Doc said, $10 [plus] per gallon - about 25% more than their low lead.
But at $10+, it is 75% more expensive than the $5.99 at a number of CA airports. The cost will probably come down with increased volumes
Congratulations Swift fuels! This is 2 choices of Unleaded Avgas for a huge number of aircraft that are actually flying a lot (R & S models, and all the legacy low compression Cessnas and Pipers). We just need to clear the regulatory & marketing hurdles to have the ASTM UL94 available to non-aviation users at our local marinas and gas stations. This will create economy of scale for pricing that even 100LL cannot compete with.