Here's one I missed from that earlier post.
The X PRIZE Foundation news scroller adds one more article to the comprehensive list from that X PRIZE Cars post. It's from the Oakland Business Review, and it's about the big auto companies and their glaring absence from the competition. You'll have to read the article to see why.
It's interesting to compare this to the Ansari X PRIZE, which the big aerospace companies sat out. However, when the dust settled, Virgin Galactic was there as a big customer to take the winner to production scale and Northrop Grumman was there for a buy-out (although conventional wisdom is that the purchase was more related to other Scaled Composites efforts that fit NG needs).
That's all well and good, but it would be interesting to get the big auto companies into the AXP competition. Could there be a 3rd category in the competition designed specifically for big automotive companies? Maybe this "big company" category would lower the MPGe requirement from, say, 100 MPG to 80 MPG. The tradeoff? Raise the required vehicles that can be produced to a much greater number, like 100,000 or more, and have more requirements to prove that this mass production will actually happen (is already happening). Since prizes on the order of $10M aren't a big deal to such huge companies, just make it $1M to show that it's a serious prize (leaving the rest for the entrepreneurs), and of course let them share in the media coverage.