The 65 MPH is not a limit on how fast it will go, or damage that will be done, but the safety factor. Towing anything above about 65 increases your stability and risk factors on an expotential scale. Winds, road defects, any instabiity factors can and do have increased impact as speeds increase. I pull our HHR usually in the 60-65 range for comfort and ease, but I have seen 80+ on at least one occasion, but would not recommend it under any situation. I do know from experience with an emergency run that the HHR gets VERY light on its feet at 85 MPH. Its gets really scary... The least bit of sidewind throws you all over the road.
Noel, Betty, one fuzzy little poodle that thinks he is a standard
2005 Gulfstream Ultra Supreme 30' 07 HHR Toad