It has been just over a month since I picked up the Kia Sorento Platinum, yet the number of features this seven-seater SUV includes still surprises me.
Heated front seats are becoming more common these days, but Kia has also added this feature to the second-row seats as well. To make sure the front seat passengers still feel that extra bit special, Kia has also given the forward pews a cooling function (something I have been using regularly during Perth's recent hot spell).
The Kia Sorento Platinum even has a heated steering wheel. While I must admit that I have not needed that function due to the afore-mentioned heat, I did turn it on briefly to test it out. I can imagine how nice it would be to wrap your hands around a warm steering wheel on a frosty winter morning.
I am also getting accustomed to the radar-controlled cruise control. While I think it is a great safety feature, drivers do need to adjust their driving style slightly to keep the car moving smoothly. For example, if you change lanes after the car has slowed to below the set speed, it can take a little while to react to the open space ahead of you.
While I am only halfway through the trial period, I am already starting to feel quite attached to the Sorento. The 2.2-litre diesel engine is one of the most refined in its class and the six-speed automatic transmission goes about its business with absolutely no fuss.
For a car that is priced under the luxury car tax threshold, there is very little else you would want in regards to luxury options.
However, the main reason for the Sorento spending time in the BoatAdvice garage was to use it as a towing vehicle for boat tests. With a maximum towing capacity of 2000kg when braked (and 750kg unbraked), the Sorento is suitable for all but the bigger trailer boats on the market. This towing capacity also makes the Sorento suitable for a large range of caravans and most camper trailers.
In the first month, the Sorento was used to tow a series of boats that weighed between 1200kg and 1700kg, which is well short of its claimed maximum towing rating.
The towing distances ranged from relatively short trips to much longer journeys that involved using the freeway and travelling at 100km/h. The thing that stood out for me in all of those trips was that there was no sign of trailer sway with any of the boats we towed.
While I tend to nurse any vehicle when towing, allowing it to slow slightly when going up an incline rather than working the engine harder, the 147kW/441Nm 2.2-litre four-cylinder diesel has more than enough torque to ensure the Kia made it comfortably up those climbs. If the transmission did drop down a gear during the ascent, it was virtually seamless. At no time did the six-speed auto start 'hunting' for gears.
The only significant change when towing was in fuel consumption, which understandably jumped around 4.0 litres per 100km more with a boat on the back than without.
For all my good impressions of the Sorento, it does have one major pitfall – it can only carry a maximum tow ball weight of 100kg, which is just five per cent of its maximum towing weight. Tow ball weight is an interesting topic because car manufacturers set the figure and then hope that trailer and caravan manufacturers will build a product that matches. To further complicate matters, different markets have different ideas about what is the ideal tow ball weight.
In North America it is generally set at around 10 per cent of the car’s maximum towing capacity, while in Europe it is a much lower figure; generally between 50 and 100kg, irrespective of tow weights.
Research conducted by the Department of Mechanical Engineering at Bath University in the UK in 2009 revealed that the ideal tow ball weight was between six and eight per cent of the trailer’s gross mass, but that is a figure that nobody seems to consider when making cars or trailed items.
All this means is that owners need to be very careful when selecting the right car to tow their boat or caravan.
So how do manufacturers determine the tow ball weight? According to Kia Australia aftersales manager Phil Murray, a range of engineering criteria is used to establish the figure, but in simple terms the rating is the maximum weight the manufacturer believes the vehicle can carry, without compromising safety or performance.
For those who can remember, the first Sorento (the BL which was launched here in 2003) had a towing capacity of 2300kg and a maximum tow ball weight of 280kg. Since then the Sorento’s towing capacity and tow ball weights have been steadily reduced as each new generation has been introduced.
Having said that, the Sorento has also undergone a huge transition over the same period. The original Sorento was a full-blooded four-wheel-drive with a ladder-frame chassis with a high- and low-range transfer box. Today the Sorento is an all-wheel-drive SUV with a monocoque frame and no low range. In other words, Kia has moved the Sorento away from being a hard-edged four-wheel-drive and into a comfortable city car that can occasionally be taken off-road.
Murray said providing maximum towing capacity and tow ball weight is on Kia Australia’s request list at the development stage of every new Sorento model. At the same time, Kia does put a high priority on the ride, handling and performance of its seven-seat SUV. But these are two diametrically opposed requests, considering the effects that towing can have on handling and performance.
“We are aware that this style of vehicle is used for towing and we want to meet market expectations,” Murray said. “But we also need to ensure that we maintain the integrity and safety of the vehicle.”
So what happens if you do increase the weight on your car’s tow ball?
According to Gary Gardiner, a technical support representative for Hayman Reese - Australia’s biggest tow bar manufacturer - you immediately put additional strain on the points where the tow ball is attached to the chassis and the car’s rear suspension. This could potentially be adding forces and strain to the car that it wasn’t necessarily designed to handle.
He added that by increasing the weight on the back of the car you also lift the front of the vehicle, which means you are taking weight off the front axles and wheels. These changes will not only make the car and trailer unstable but will also adversely affect the steering and braking capabilities of the vehicle. The act of braking also adds additional load to the tow, which further exacerbates the problem.
In regards to the Sorento, this means there are going to be some boats and caravans that it cannot tow, despite them falling under the 2000kg maximum tow weight.
But before dismissing the Sorento as a legitimate towing vehicle, there are some quick and easy remedies you can make to adjust your tow ball weight.
Gardiner says the first thing you need to do is to establish the tow ball weight of your trailer or van. The easiest way to do this by purchasing a tow ball weight scale (the Hayman Reese tow ball weight scale will measure up to 350kg and costs under $100). These scales simply fit under the tow hitch of your trailer and give a reading when you lower the trailer onto the hitch. Make sure the trailer is on flat ground and that the wheels are chocked first by winding the jockey wheel down until the scale is taking all the weight.
Gardiner says that if your trailer is too heavy at the tow ball, you can reduce that load by removing some weight off the front of the trailer. With a boat, this could be as simple as moving the spare wheel, while in a caravan it could just mean adjusting the way you pack it by moving some of the internal weight to the back. But this does not mean pushing the load all the way to the back of the caravan, because excess weight can lift the back of your vehicle up by having the load distributed too rearward. Ideally, you will want most of the weight either over the axle of a single-axle trailer or between the axles of a dual-axle trailer.
As an example, I managed to reduce the tow ball weight of my boat trailer from 120kg to 100kg simply by removing the spare wheel from the draw bar.
Tow ball weight is something a lot of us don’t pay enough (if any) attention to, but by taking a few minutes to ensure everything is compliant you could save a life. When the load is done correctly, your car and trailer should be sitting nice and flat with no sign of strain on the front or rear suspension of your car.
Getting it right will also help ensure the trailer tows well, as well as serving to reduce the chances of encountering trailer sway. But remember that it is not just the tow ball weight that plays a part in this. Testing has shown that other factors, like driver skill, speed, heavy-vehicle air turbulence, weather conditions, road surface undulations, wheel bearing condition, trailer-brake adjustment and tyre pressures, can all influence trailer sway.
To take the focus back to the Kia Sorento itself, there has been plenty to like about the car as a tow vehicle, from the way it performs under load, to the reversing camera that enables you to back the SUV right under the tow hitch without any assistance or guidance from a friend.
But despite having a maximum towing capacity of 2000kg, as a general rule, it is only going to be suitable for medium to small boats and caravans.
Note: Interior heater controls image is of Kia Sorento SLi.
Kia Sorento Platinum
Date acquired – November 2015
Odometer reading – 6387km
Travel since previous update – 1251km
Consumption since previous update – 9.1L/100km