I don't know the specifics of your particular model, but US cars generally have to meet different specs than their European look alikes.
I think you have to believe the manufacturers ratings for the US model, unless you bought a European model and had it shipped.
If you did that, it would have to be modified to meet US specs and your back at 1000lbs.
The difference used to be shock absorbing bumpers, full safety glass, and catalytic converters.
Which adds quite a bit of weight and lowers the horsepower/ aka tow rating.
Since it is a vehicle without a real frame, I wouldn't think about going over the rating. There are a lot of things that go in to the rating besides power and weight.
