It must depend on the sources. Those are the numbers I remember from cars.com a few years ago for 97-98 years, but they're not listed anymore for the older model cars now. The newer 99, 2000-2003 weighed a little more and then 2004 and newer was at least another 100 lbs for the 4 door compared to the 97-03. 1992-1999 Pontiac Bonneville: Full Review - Consumer Guide Automotive and 1997-2004 Buick Regal: Technical Specifications - Consumer Guide Automotive both list 3446 lbs for the Regal and Bonneville so I don't think that's right. Regal was about 3650 and a 4 door Grand Prix was about 3500 lbs. It seemed to go up in steps of 150 lbs cause the 2 door GTP was about 3350. I remember making a post here before with a list of weights or some measurement I compiled, I'll have to look.
