[brucepick]

My quick-and-dirty mental calculator says the 175/70-14's have nearly exactly the same diameter and circumference as the stock 185/65-14's. So no "rubber overdrive" effect there. The slightly skinnier 175's will have a slight aerodynamic advantage due to slightly less frontal area pushing against air.

I avoid braking for curves and corners so I've not gone to the skinnier ones. I need the traction. But you could make a case for the 175's. I definitely would not go wider than 185 if fuel economy is your goal. In addition to pushing more air, wider tires will "scrub" more whenever they aren't aimed EXACTLY in line with your direction of travel (which is much of the time I'm sure).

Go to TireRack.com. Look up the size(s) you're interested in. In left hand filter options column, all the way down, filter it for only Low Rolling Resistance tires. LRR tires will definitely help. I've had two sets of Kumho Eco Solus. Both had belt separation issues long before the tread wore out. My Michelin X-Ice II's (winter tires) have performed and held up superbly. Next time around I want Michelin summer tires.