I recently filled my Nissan Altima Hybrid with Shell gas vs. my normal "bargain brand". I have seen an increase in over 2mpg on this tank. (according to my dash readout). I admit the weather is turning slightly warmer here in New England, but I'm still running the heater and most mornings are still below freezing. Just wondering if anyone has experience getting better mileage with certain brands of gas. BTW, as far as I can tell, all the brands around here contain 10% ethanol.