The front struts may show signs of wear, or be excessively bouncy ride at freeway speeds. This may begin to occur at around 75,000 miles.Google+
Car Problem Reports
Pontiac Bonneville Front Struts May Wear at 75,000 Miles
Pontiac Bonneville Problem
Average Mileage: 122,666 mi (83,000 mi - 165,000 mi)
Visitor, 2005 Pontiac Bonneville, 83,000 mi
Rear end very boun cy at highway speeds. Rear end kind of fishtails to the side. Didn't know it had air shocks when I bought it. When rear brakes were replaced I was told one air shock hydolic lever looked bent.
Visitor, 2003 Pontiac Bonneville, 120,000 mi
this car has always shimmied at around 75 mph. 2003 Pontiac Bonneville SLE. Otherwise, it's a nice car except the turning radius is like a Mack Truck; two tries to park every time. Play in steering since new, too.
Mechanic says front struts should be replaced and also sturt plates should be included in replacement Estimated price with alignment $1K. This seems high in price.