I'd appreciate a mini lesson/thoughts on using both in the same car. Years ago cars were recommended 91 Benzene, which isn't available anymore, but encouraged to use 91 Gasohol even though it didn't get advertised by manufacturers. I had reservations as cars weren't apparently tuned for it. Most people tell me that it didn't cause any damage, just slightly sluggish. I'm seeing cars recommending 91 and E20 by the manufacturers. I guess that I would use E20 when I can but is there a problem with constant mixing? I'd be grateful for thoughts on how much I should trust the hype.

On cars designed to use these fuels no problem the ECU does the maths, if your car can run on E20 and the garage hasn't got E20 anything else will do except diesel or E85.

Not seen E85 here though.

Don't trust the hype trust the manufacturer.

I cant get E85 up here, and only in the last 6 months has E20 become more widely available. As for Slightly Sluggish its in their minds unless they drag race.

I have a suzuki swift and don't notice much difference between E10 and E20 (91). Performance and economy seem roughly the same, so I stick with E20 as it works out cheaper. No problems with mixing these fuels.

Only 91 Gasohol seems to show a tickover variance according to my non boy racer friends My Mad Head friends just moan about anything under Rocket Fuel specs. I like the Swift by the way culicine.