There may be different answers to your question....and it's possible that the (curb weight) as listed in the web may or may not be accurate enough.

I use a Gtech Pro meter that measures my 1/8 mile 1/4 mile times as well as HP and Torque. A really cool device that is endorsed by the NHRA for accuracy and it requires (very minor) calibration. One of the things it asks for is the exact vehicle weight.

Well, the advertised (curb weight) on the web is not the same if you changed the heads, intake, wheels/tires, etc.etc.etc.. it does not account for your weight or gas/water in the tank, all of which could effect the weight of your car by a few hundred pounds.

I use the local feed store that has scales built for farm truck to drive up on and it's accurate within a few pounds.

Just an alternative if you want to be accurate.