In these times of Tesco car parks being full of SUV-style cars, the 4×4 is not quite as it seems. After years of being the preserve of the country elite, 4x4s began appearing in a less muddy format more and more often.
With most off-road vehicles never going off-road at all, manufacturers quickly realised they didn’t need to include full-time four-wheel drive (shortened to either 4WD or 4×4) systems in their SUV models – in fact, quite often they didn’t need to include any kind of 4WD system at all. So the answer to the slightly odd title question is ‘most of the time’.
Today, many of the chunky-looking SUVs on the market are actually “faux-by-fours” with zero off-roading credentials whatsoever. Others have varying levels of mud-plugging ability, and only a few are genuinely capable of going a long way from the safety of a nice piece of Tarmac.
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What is four-wheel drive?
Four-wheel drive (4WD) means that both the front wheels and rear wheels are used to move the car. Most conventional cars are two-wheel drive (2WD), driving either the front or rear wheels.
The idea behind getting all four wheels to drive the car is to share the load more evenly, meaning each wheel has less work to do. This means that the vehicle is more likely to maintain its grip on slippery surfaces, as all four wheels are contributing and each driving wheel is less likely to spin as you push down on the accelerator.
There are various ways of providing four-wheel drive on modern cars, so let’s have a look at how it’s done.
Before we had a hundred different shapes and sizes of SUV, there were only a handful of ‘real’ four-wheel drive cars available in the UK. These included a few Land Rover and Range Rover models, as well as some very capable Japanese offerings like the Toyota Land Cruiser and Hilux, the Mitsubishi Shogun, and even small Suzuki models like the Jimny and its predecessors. All of these vehicles had one thing in common; they all had traditional 4×4 systems.
Most vehicles using this sort of 4WD/4×4 system have mechanisms to lock the differential(s) to make sure left and right wheels are getting equal drive. This last bit is critical because a normal car will always push the power to the wheel with least resistance. Anyone who has ever got a car stuck will have seen this, as one wheel spins furiously while the car goes nowhere. A locking diff system will mean that power goes equally to either side, and this is what gets you out of the mud or snow.
Some models allow either the front or rear wheels to be disengaged, turning the vehicle back into a two-wheel-drive model when conditions did not require the extra traction, such as on-road driving. This improved fuel economy and wear on components, especially at the higher speeds achieved on Tarmac compared to gravel or mud.
Most traditional 4×4 systems also have a separate control level for high and low ratios. In normal use, the vehicle would be in high ratio, and in low-speed off-road situations the driver can switch to low ratio for improved take-off in low-grip conditions. This is a level of off-roading far beyond what most modern SUVs will ever need.
In the 1980s, car manufacturers started exploring the idea of using four-wheel-drive systems for on-road performance rather than simply off-road utility. This came about as performance cars became ever faster and harder to control. Spreading the drive across four wheels rather than two means that the car has more grip, and can go faster and/or maintain its performance better in slippery conditions.
Two of the big drivers of this development were Audi and Porsche, who started using the term all-wheel drive (AWD) to describe what was basically a 4WD system optimised for on-road use. The other major difference was that these vehicles used systems to vary the amount of drive going to the front and rear wheels, rather than a simple fixed 50:50 split.
With over 30 years of development, many of these systems have become highly advanced, and can control the amount of drive going to each wheel to ensure best overall grip and performance. There are a variety of systems used to achieve this by different manufacturers, but the principle remains the same.
Manufacturers, typically, have ignored simply calling these systems ‘all-wheel drive’ and applied their own terminology instead: Audi kicked things off with the name quattro, but these days BMW calls its AWD models XDrive, Volkswagen used to use Syncro but now uses 4Motion, Mercedes-Benz uses the name 4Matic, and so on. The principle is the same; a variable all-wheel-drive system that is largely designed for on-road use, although it may well be very competent in a number of fairly gentle off-road scenarios.
Some vehicles have different power units driving each axle. For example, several hybrid or plug-in hybrid SUVs use their petrol engine to drive the front wheels and their electric motor to drive the rear wheels when it’s needed.
Some are even clever enough to switch between driving as a front-wheel drive petrol car, a rear-wheel drive electric car or an all-wheel drive hybrid at different times, depending on circumstances.
In the world of electric vehicles, some cars have two electric motors – one that powers the front wheels and one that powers the rear wheels. It’s also possible to have four-motor electric cars, where each wheel is driven by its own electric motor for ultimate performance and control.
Two-wheel drive SUVs
This group of vehicles is the answer to the question posed by the title of this article – when is a 4×4 not a 4×4?
Not every butch-looking SUV has genuine off-roading hardware underneath the flared wheel arches and side steps. In fact, these cars may be no better than a common hatchback or saloon when the going gets muddy or snowy, and the genre has been dubbed ‘faux-by-four’ by critics. They’re also often referred to as ‘crossovers’ or ‘soft-roaders’.
Car companies worked out that customers loved the look of big four-wheel-drive vehicles, but rarely do the majority of these cars go anywhere off the beaten track. In fact, they are mostly used for popping down to Waitrose (or Aldi, if you prefer) and dropping the kids at school. In other words, normal car stuff.
So, reasoned the manufacturers, there was absolutely no need to burden their vehicles down with heavy and expensive 4WD running gear. Take out half the drivetrain and you get a vehicle which has better performance, better economy, lower emissions, lower servicing costs, is much cheaper to build and – importantly – still has the all-important ‘lifestyle’ appeal for buyers. As long as they don’t want to actually act out those lifestyle feelings by getting their car muddy.
What has been most pleasing to manufacturers, however, is that the remarkable appetite from buyers for these vehicles has allowed them to charge hefty premiums for all sorts of soft-roaders, crossovers and other marketing buzzwords which describe cars that look like trucks but are not.
Basically, Volkswagen can butch up the looks of the Golf, stick a Tiguan badge on it and charge a huge premium for the privilege. The Honda HR-V is little more than a Jazz on steroids, the BMW X1 is a 1 Series hatch on stilts, the Nissan Juke evolved from the Note hatchback platform, and so on across pretty much every single car brand. Some of these are available with a four-wheel-drive option, but by default they are simply two-wheel-drivers with added height and weight.
For a huge number of drivers, a 2WD SUV is the perfect option, as they never intend to drive off-road anyway. Just as long as they appreciate that their car will be no better (and often worse) than a run-of-the-mill hatchback when it starts snowing, since these vehicles generally offer nothing in the way of extra traction or off-road capability.
Servicing and running costs
As with all cars, SUVs need servicing and looking after. It will probably come as no surprise that four-wheel-drive and all-wheel-drive cars might need some extra attention, due to the extra wear and tear created by having twice as many driving wheels and associated assemblies.
If your car is a 2WD SUV, your servicing and running costs should not be massively different to a regular hatchback or saloon, so make sure you are not being ripped off by the dealer or garage just because your car is an SUV. Your tyres, however, may be significantly more expensive than those found on a conventional hatchback.
Whatever type of SUV you drive or choose to buy in the future it is important to understand what it is capable of. It is also important not to be lured into buying a large heavy two-wheel drive car under the false impression it might be useful if it starts snowing… because it may not be.
This article was originally published in September 2016, and comprehensively updated in May 2021.