I've had my dogs in car harnesses for over 10 years. I began using a walking harness (see this earlier post) and have since graduated to a Bergen harness as I felt it provided better protection, offered more chest coverage and therefore, less impact harm to my pup. Bella is never in the car without being in her harness. But today, I came across an interesting article that relayed test results from different dog harnesses and the Bergen was not a leading contender. In fact, for a 75-pound dog, it proved catastrophic meaning the restraints broke, launching the dog.
With a bit more scurrying around the Internet, I was able to locate the actual study and am linking you to it, so you can see how the testing was done. This is the first time I've read that a study was even conducted. It seems the Sleepypod Clickit harness was recommended in all dog weight ranges (small: 25; medium: 45; and large: 75 pounds).
The Clickits are not cheap, but it could save your pup's life.