The true kerbweight of a tow car is an elusive thing. That’s something several owners of the new Hyundai Tucson have found out to their considerable concern.

The Tucson is a very capable tow car, and we’ve reviewed it favourably in the magazine, on our YouTube channel and at the Tow Car Awards. However, since the car was launched in 2015, Hyundai has given a number of different figures for the car’s kerbweight.

It’s a long story, so I’ll give you the short version. Last September we noticed a discrepancy between the kerbweight figures in Hyundai’s press pack for the Tucson and those it published online. We queried this with Hyundai, and were told that the heavier figures we’d seen on the internet were correct. These are the figures we published in our tow test of the Tucson, and which are given in our YouTube video review.

Move on a few months, and we booked a Tucson for evaluation at this year’s Tow Car Awards. Whenever a manufacturer enters a car into the competition, we send a questionnaire asking for various facts, figures and information. I usually fill out the section on kerbweights and towing limits in advance for the manufacturer, and we ask them to check it. There’s a note on the form and in the email which accompanies it reminding manufacturers that we publish kerbweights including 75kg for the driver.

I pinged the form over to Hyundai, and it pinged back with kerbweights much lower than I was expecting. To be absolutely sure, I checked the weights Hyundai had given against those on its website and there was a big discrepancy.

To be absolutely, 100%, beyond-any-doubt sure I raised this with Hyundai, and was told the questionnaire weights were correct and that the weights on its website had been published in error, and would be amended urgently.

So, having failed to cut a long story short, the new, lower kerbweight is the one we published with the Tow Car Awards review of the Tucson.

Since the Tow Car Awards results were published in June, we’ve been contacted by a number of Tucson owners concerned that the car doesn’t weigh as much as they expected.

For example, the high-spec Tucson 2.0 CRDi 185PS Premium SE Auto which we tested last year had a kerbweight of 1779kg, according to the brochures Hyundai and its dealers were using at the time. That gives an 85% match figure of 1512kg. Today, Hyundai quotes a kerbweight of 1615kg for this model. That’s some 164kg less, and gives an 85% match figure of 1373kg.

To muddy the waters further, one reader took his car to a weighbridge on our advice to check the true weight of his Tucson. Despite being a two-wheel-drive manual and not having a full fuel tank or any people onboard, the car weighed 1860kg.

So, what’s the true kerbweight of the Tucson? And has Hyundai made a mistake in publishing new, lower figures, given the apparent weight of the car belonging to a Practical Caravan reader?

We put our concerns to Hyundai, asking firstly how it calculated the two sets of published kerbweights: “Hyundai Motor UK used to publish the maximum kerbweight of each engine powertrain variant and has now changed to publishing the minimum value equating to the Mass in Running Order (from the Whole Vehicle Type Approval) minus 75kg (driver weight),” a spokesperson told us. In other words, Hyundai says the old figures weren’t wrong as such, but were maximums for a well equipped car, whereas the new figures are bare minimums.

The trouble is, we argued, many owners have bought cars based on the originally published figures, and might have made different decisions if the new, lower kerbweights had been available to them. However, Hyundai argues that in the eyes of the law the towing capacity of the Tucson has not changed: “There has been no change to the advertised towing capacity of the Tucson as per the WVTA legislative process. The maximum permissible vehicle weights, maximum permissible towing weights and therefore, the maximum permissible Gross Train Weights have not changed and therefore there is no reduction in the Tucson’s towing ability or capacity.”

We can see where Hyundai is coming from, but at the same time the kerbweight and a car’s matching ratio is a key part of most caravanners’ car buying decision. The 85% guideline may be a rule of thumb rather than a legal requirement, but tow car drivers should be able to compare the specification of different cars accurately and consistently. Most manufacturers publish minimum kerbweights (with or without 75kg for the driver), or otherwise they publish a minimum and maximum figure. Because Hyundai initially published a maximum weight, the Tucson may have been bought by caravanners who would otherwise have made a different buying decision.

In fairness to Hyundai, the whole issue of how to define kerbweights is a mess, and not one of its making. The term used in European type approval legislation is, strictly speaking, Mass in Running Order, and includes 75kg for the driver (or 68kg for the driver and 7kg for sundry luggage if you really want to be pedantic), and a 90% full fuel tank. But almost no motor manufacturer website or brochure refers to the Mass in Running Order, with ‘kerbweight’ or ‘unladen weight’ being the more common terms. Sometimes these weights include the 75kg for the driver, sometimes they don’t. Many manufacturers make it clear whether the 75kg is included or not, but by no means all. Some (my finger is pointing at you, Vauxhall!) don’t publish kerbweights in its brochures at all.

So, what’s the solution? Well, we’ve urged Hyundai to write to owners (at the very least those who have bought their car with towing gear) to explain the change to the definition of kerbweight it has used. It’s considering whether to do so. 

For our part, we’re going to make a note on our video review to explain the same.

In the long run, though, we need to get away from having a multiplicity of different terms and definitions, and have one clear, consistent standard for kerbweights that everyone in the industry follows. Will it happen? In the short-term, I very much doubt it. But if caravanners are to make informed decisions about which car they should buy, it really has to.