I've read multiple articles on this issue and this one sums it up well. There is only one crash tested dog crate made, it's expensive, and it is only available in the UK. The best solution right now is to use a safety harness meant for car travel on your dog. Be sure it attaches at the back of the dog and has padding around the chest. I use the Petmate AKC Dog Seat Belt, which you can order on Amazon.
Here is the article:
Why Dog Crates Are NOT Safe :: Ruff Rider
For those of you that live in the UK who are interested in the crash-tested dog crate, you can go to the following link. This company also sells higher quality, crash-tested, safety harnesses.
crash tested car crates