My 2003 SportDesign has a 17 gallon tank. I always use Circle K 93 or Marathon 93, and get 20's for MPG every tank. Haven't noticed a difference for winter, maybe because of snow mode keeping throttle low. I've only done the timing belt as maintenance, still plan to do plugs/coil packs/wires soon and fuel pump filter (in tank). Car has 185k now, and the previous owner history/maintenance is sketchy.