This is an increasingly common problem for people who carry big loads and especially for those who tow heavy trailers. In some cases, as you've discovered, it's very easy to get perilously close to the GVM limit by loading up the vehicle with whatever you're carrying. And that's the catch; the vehicle's GVM includes everything on board including passengers, fuel and whatever accessories you've added to the car, not to mention the actual payload.

Earlier this year, Queensland changed its rules regarding GVM upgrades, but you would need to speak to a specialist workshop that deals with this type of work and is familiar with the QLD regulations which may vary from other states and territories. Companies such as Pedders are qualified to carry-out GVM upgrades on some vehicles and have the engineering experience to offer a package that is certified before it's fitted to your vehicle. Whether the Sprinter's body construction has any bearing on the availability of such a kit is another thing you'd need to check with a specialist.

The problem with exceeding your car's GVM is that it makes its potentially unsafe to drive for both you and other road users. You'll also find yourself in line for a fine and your insurance company is likely to disown you in the case of a crash in an over-loaded vehicle.