I've found these:

Chevrolet Volt Water Trough Test - At the Milford Proving Ground, the Chevrolet Volt undergoes a water trough test to measure how well the battery inside the car will be sealed. Watch the vehicle splash through the water and learn how the test engineers measure the results.
http://www.youtube.com/watch?v=YUJDrZT5LCA

Chevrolet Volt undergoes real world durability testing - real-world durability testing. This test simulates100,000 miles of driving on the roads of GM's Milford Michigan Proving Grounds.
http://www.youtube.com/watch?v=lRm6xH91fok

Chevrolet Volt Corrosion Testing - The Volt and the Volt battery go through a series of corrosion tests.
http://www.youtube.com/watch?v=aA0ZoOCybbc

Chevy Volt Durability Testing: Potholes & Belgian Blocks - As part of its durability testing, the Chevrolet Volt takes on potholes and the Belgian Blocks at GM's Milford Proving Grounds.
http://www.youtube.com/watch?v=2CAW_QfRUZE

Chevrolet Volt Dust Intrusion Test in Yuma, Arizona - To test for dust intrusion, the Chevrolet Volt drives behind a Chevrolet Silverado on a test track in Yuma, Arizona
http://www.youtube.com/watch?v=CxBl142n-v4

Explaining the Chevrolet Volt Grade Load Test - Chevrolet Volt lead durability testing engineer Steve Pratt describes a mountain grade test in Yuma Arizona. The test measures how the vehicle performs while driving up mountains.
http://www.youtube.com/watch?v=imttz8sLxdw

Durability testing on Chevrolet Volt charge port, trunk & fuel door - the durability tests on the Chevrolet Volt's trunk, charge port and fuel door. Learn about the thousands of slams each door undergoes to check for quality.
http://www.youtube.com/watch?v=k6DoejbN3Po

bump ... perhaps many of the new owners or lurkers have not seen these.

Thanks for this!
It's easy to forget all of the testing the car guys do on their vehicles and these clips highlight it!