From what I read, they saw how well the stratagy was paying off for GM to sell "flex-fuel" trucks that don't get any better real world mileage, but the EPA gives them some fictionaly high CAFE rating because the ethanol portion of the rating system skews the number irrationally high. This means that while GM has not really increased their real world CAFE, they are given credit for raising it and don't have to sell as many non profit generating cars.

Ford is just following suit, and focusing on the ethanol crowd where the investment is low to convert the current engines into E85 compatable while raising the CAFE number in turn.

IMO, it is a crummy strategy, but as long as the rating system works like it does, we won't see it change.