http://www.epa.gov/otaq/regs/fuels/r...rf/rfgperf.htm
lists gasoline properties for various areas. Doesn't really answer your question, though.
Did NY and CT just implement ETOH replacement for MTBE? Looks like it happened in 2004. If that is mandated by the state, you're out probably SOL unless you can fill up outside northern NJ or in PA. I doubt NY will move to strike oxygenates now that the EPA allows it- they're pretty solidly behind ethanol.