... I now put out the same emissions but go 5% less miles.
if you're burning 10% less petroleum you are producing
less emissions, except for formaldehyde from low E blends, which would be taken care of with a catalytic converter
I've been running E10 in my old trucks and small motors ever since it was first offered here decades ago, with zero problems, and think the mileage difference is way overestimated - has much more to do with how you drive, and with small motor problems it has more to do with infrequent use and poor storage
Bill