You could be looking at an engine that has a fuel-system problem. A lack of fuel pressure or volume (or worn injectors) can play havoc with a turbo-diesel engine at higher speeds thanks to the higher loads being placed on it. You may also have a worn or damaged turbocharger or perhaps an inlet manifold that is partially blocked from fumes and soot that are part of the vehicle’s emissions system. The problem could even be due to a blocked DPF in the exhaust system which could require manual cleaning or even replacement.

But this is another example of a car that’s still under warranty being the responsibility of the manufacturer to put right (provided the vehicle has been serviced correctly). Give the dealer very chance to fix things, but if they throw their hands in the air, then Kia Australia’s customer service department is your next stop.

The allowable maximum tow-ball weight for the Sportage will have been calculated by Kia using all the available information from the car's weight distribution to the spring rates, the ride height and wheelbase measurements and even the way the rear structure of the car is physically constructed. So that's what you should stick to and, yes, 100kg is the official tow-ball weight for this vehicle.

The theory that holds that tow-ball weight should be 10 per cent of the towed weight (while the reality for a lot of makes and models) is really just that; a theory, a rule of thumb, and definitely not a hard and fast rule. As such, there's nothing to force car-makers to stick to it. Which is why Kia hasn't for the Sportage.

There's another school of thought in other countries that the tow-ball weight should actually be closer to five per cent of the towed mass, at which point the Kia's limit starts to make more sense.

The Kia Sportage SX starts at $35,000 in manual form and $37,000 for the automatic variant. The better equipped, more powerful GT-Line petrol version is available only as an automatic and costs $49,370. Those prices do not include on-road costs which will vary from state to state and even region to region.

The current Sportage was launched in 2021, so we can possibly expect a mild facelift sometime in the 2023 calendar year. But being such a new design, the upgrades are not likely to be major ones, so there’s no reason to hold off buying now or when supply allows.