As the Chevy Volt gets closer and closer to production, GM engineers have been pushing the car to the extremes in field testing. This week, a pre-production Volt has been going through several tests in Yuma, Ariz., where the average daily high during June is 104 degrees F.

First there's the Hot Soak, in which the car is left in the sun for hours, where the temperature inside of the cabin can reach more than 175 degrees. Today, engineers opened up the Volt at a temperature of 138 degrees, then tested the electronics and air conditioning before taking it out on the test track to check for handling and performance issues.

Then there's the Grade Load test, in which a towing dynamometer is attached to the car to simulate mountain driving. The test was performed at temperatures above 100 degrees to see how the engine and chassis would perform in hot, mountainous conditions, as the dynamometer was adjusted to simulate grades of incline between 2 and 10 percent.

Finally, there's the City Cycle test, which is performed two to three times per day. This is to test the Volt's performance in more common driving conditions, testing how its components respond to high heat during "repetitive, cumulative use."

Check out the pictures for what is your probably your first glimpse of what a Chevy Volt looks like dirty.