However, those who take the federal and state tax breaks for their heavy SUVs are happy to accept the GVWR as their vehicle's official weight. After all, they must be over 6K to get the write-off. Yet now they're arguing that the actual weight of the vehicle as it rides along California streets may—may—be slightly under 6K. Since the weight at any given time could depend on how many bags of groceries are in the back, and very few residential streets have their own scales, we will never know. (Of course, this isn't an issue for the Hummer and some other vehicles, which break the 6K barrier by any measure.)
In other words, owners say their SUVs are over 6K when it benefits them and under 6K when it burdens them.
Here's my solution: Pick a number and stick with it. If owners of heavy SUVs prefer to use the lower curb weight, fine with me. I won't squawk about them cruising down streets with 6K limits, as long as the feds make them ineligible for 6K tax breaks. But if they want to hold onto their write-offs, and the ability to claim them using the GVWR, they shouldn't turn around and argue the GVWR doesn't apply in other governmental contexts as well.