Maximum pressure has nothing whatsoever to do with the vehicle. It is determined by the construction of the tire. Many tires have a maximum cold inflation of 35 PSIG because they cannot safely tolerate any more internal pressure. 4 of mt 7 vehicles have tires which permit 44 PSIG (3 BAR) inflation because they use 6 ply carcasses and are made to withstand the pressure. Obviously, the rolling resistance is slightly lower at higher inflation. There are other factors affecting rolling resistance, but inflation is very important.
Tires with a single ply sidewall construction are cheaper, but also tend to have higher rolling resistance.
The maximum GVWP is indicated on a label affixed to the LF door pillar, glove box door, or some other conspicuous place. The weight rating is indicated in total load, passengers included, so you'll have to do the math.
As long as we are on the topic, I have recently heard tire shops advertising that "filling your tires with nitrogen can save fuel." That is a completely misleading claim, based upon junk science and praying upon the unsuspecting. You could fill your tires with hydrogen and it wouldn't make a difference. The key is that the tires are at the proper inflation, regardless of what is used to inflate them. That said, nitrogen DOES have some benefits, however. Most importantly, pure nitrogen will help preserve the tire carcass slightly over time. However, most drivers will wear out their treads before rotting out the carcasses from inside. Also, pure nitrogen can have a slightly lower tendency to change pressure with temperature changes compared to atmospheric air, but only slightly (Boyle's Law is still in effect here). I believe that is the basis of the advertising claims. However, you can do just as well by checking your tire pressures periodically, just like the owner's manual stipulates.
Personally, I'm using a partial mix for inflating tires, with about 78% nitrogen.