If I had to guess, I would say your vehicle was designed to haul around 800 pounds, including passengers. The best way to tell is to get the GVWR (Gross Vehicle Weight Rating), which is probably on the door pillar. GVWR is the total allowable weight of your vehicle loaded. Then get your car weighed (with a full fuel tank) at a truck stop for about $5.00 and subtract that from the GVWR. Whatever is left is what you can haul safely (assuming it is loaded correctly). Good luck.

Semper Fi, George