回複：結論：美國車減重不影響安全。日本車減重是偷工減料，影響安全。

Check this.

http://www.youtube.com/watch?v=yBKFKhcfmbQ

Current F150 frame strength is 4x of tundra's.
Even if new F150 has only 1/4 of the old F150's frame strength, it still breaks even with tundra.