Auto News has an interview with Chief Engineer Takeaki Kato...
From the center to the rear is basically new, with no commonized parts. The front bumpers and crash box are totally different. But while the inside rocker panel is reinforced, the outside structure is the same.
For some parts, there was no need to change. We could carry over the wheelbase because the RAV has a good package, with good legroom. But things like the suspension bushings are different. We used the same geometry of suspension, but all the parts are different.
Things like the rear suspension members were retooled to make a tighter chassis. We retooled all the RAV tooling to make it more severe, with better fit and rigidity. The accuracy of the parts was very important, to get the body rigidity tighter.