This has to be my favorite top gear episode
http://video.google.com/videoplay?docid=2402060372341641699&q=top+gear+toyota&pr=goog
http://video.google.com/videoplay?docid=2402060372341641699&q=top+gear+toyota&pr=goog
Or maybe load the bed with concrete bags and drive over some speedbump and a couple curbs. I figured with a test, you'd want to test something you may conceivably use it for. Most trucks can be submerged without any problem once the flooding it fixed. The long term effects are what will kill it.