As a new Energi owner the spare tire issue is on my mind. Having never owned run-flat tires I do understand the general concept thereof and it looks to me like like even after losing all of the air most of them run about another 50 miles at about 50mph. So here's the question: wouldn't that type of tire be almost a no-brainer for this particular car? Furthermore, why wouldn't Ford add them as original equipment? My first thought was cost, though a quick search on Tirerack shows a few Michelin options at or below the cost of the OEM tires. Any thoughts? Maybe I'm missing something here.