Shift to Lighter Unibody Architectures No Slam Dunk

In this time of record-high fuel prices, the idea certainly sounds good: migrate some of the industry’s big-volume models – SUVs and pickups – from their body-on-frame architectures to the lighter, unitized body structures on which most cars are built.

With a 35-mpg (6.7 L/100 km) fuel-economy mandate now on the books, everything must get lighter, and if SUVs and pickups are going to remain viable, it seems logical to try eliminating their bulky frames, a single (though ...