[MetroMPG]

We already know that it's going to help MPG.

The question GM is looking to answer is whether it's going to help enough on the EPA test cycles to justify it on some GM bean counter's spreadsheet. This is probably more about meeting CAFE requirements, not providing better MPG to people in the real world.

Unfortunately, precisely ZERO of the EPA test cycles measure fuel economy over long distances at 70+ mph, like much of America travels.