Ymbiz

Good question. It probably would be best to compare ST vs. the oe tire, but I failed to note the numbers. On longer trips, we also often have a roof box, a bike rack, and drive at 75mph+, so fuel economy of the tires isn't out biggest problem:). Back when I had similar mods on our 2011 Prius, I think I saw maybe a 10% drop. But the OE Prius tires were ridiculously high efficiency and very uncomfortable; the comfort improvement alone was worth $8/month in gas costs to me.

Overall, I would expect the tire wear would be similar to non-turbo Focuses. For reference, I had about 25k miles on the Energy Saver Michelins with no wear issues at all. In my case, because the 18s were already well worn from track events, I didn't care about tire wear and ran them at lower pressures to increase comfort. I probably went too low on the rears (32 psi iirc) and given the extra weight of the battery, saw some increased inside tire wear. When I get new tires, I'll get the alignment done, try 35-36 psi cold, and monitor to see if that pressure is ok. I would expect the rear sway bar to have no impact on tire wear. With really aggressive cornering, the big rear bar might reduce front tire wear by reducing understeer. I wouldn't expect the rear shocks to affect the tire wear except if the original shocks are completely worn.

In case it helps anyone, I have found it's possible to dramatically improve the cornering/handling of the C-max while keeping the ride quality very similar to stock with some relatively low cost mods. Rear swaybar - This is a *very* cost effective way of making the cmax more eager to turn in, and minimize understeer. A gen 1 Mazdaspeed3 rear sway bar is cheap and fits the C-max; you can use stock Ford end links. Summer tires - A big rear sway bar + decent summer tires will make the Cmax very responsive to steering inputs, and way more fun to drive. Swapping the wheels from my Focus ST, the grip levels actually feel very similar between the Cmax and ST. Comparing sound levels, the worn Focus ST tires (235/40/18 Goodyear Eagle F1 asymmetric 2 @3/32" tread depth) are 1-2db louder at 70mph on smooth concrete freeway vs. the OE Michelin Energy Saver AS tires at @5/32" depth. Rear shocks: Koni adjustable yellows for the Focus (8040 1351 Sport) fit; no drilling required. At the softest setting, the ride is close to stock, but still reduces the C-max's tendency to rebound and porpoise. I'm pretty satisfied with the soft setting, but will probably adjust them a bit stiffer at some point. With just the sway bar and tires, the C-max is more engaging in corners than my 2013 Focus was with similar mods. I think it's almost as satisfying in turns as one of my favorites, my 2005 Mazda 3.