gas mph 05 vs 08

[lasvegash2]

in my 2008 h2 sut i tried to run 87 and 89 and it hesistate under wot...but with 91 it pulls really strong...the hummer dealership told me to run 91 oct in it when i bought it and now i know why

[CUZICAN]

I've run 87, 89, and 91 octane in my 08 and did notice perfomance differences with 87 but between 89 and 91 no big difference. Gas mileage had been right around 13 and up to 14 if doing a lot of 60mph driving out in rural areas.