jshel.. The mileage on the car is way better than ever imagined - surprising. Last weekend I averaged a tad over 18 mpg - not that it matters when your pushing 540hp/490tq in a 408, and an 0.82OD Tremec. I would say nearly 95% highway. I am sure that with the 0.63OD Tremec the mileage would improve as well (guessing 2-3 mpg).
One noticeable item, is that once you let off the gas, the car really begins to slow down. There is enough rolling resistance even with the 0.82 that the speed drops off. Probably, not so noticeable with the 0.62.
My only concern was leaving the car un-attended for about 1:15 minutes. but the schools had local police in the parking lot.
