If buying a car can be a nightmare, then buying an off-road vehicle can be a complete disaster. Unless, that is, you really do your homework.
There are so many different kinds of off-road vehicles on the market that you could easily end up buying the wrong one for your purpose, so you need a very clear idea of what you want to do in your 4×4.
If you often go off road because of your job, or because it’s simply a part of your lifestyle, then you’ll need one of the more expensive dedicated 4x4s. If, however, you use the vehicle for commuting for most of the year, but go off-road occasionally, then a less expensive 4×2 may be ideal for you.
Most off-road vehicles on the market these days fall somewhere between these two poles. Off-road vehicles are often seen mostly as SUVs, but double or single cab bakkies (with or without 4WD) also make excellent off-road vehicles.
Some manufacturers like to use the term “all-wheel-drive”. To me, that means the same as 4WD, unless the vehicle has more than four wheels!
Two-wheel drive only: This kind of vehicle is a sensible choice for somebody who wants the extra ground clearance, lower gear ratios and torque delivery of an off-road vehicle without wanting to put up with any 4WD-related hassles. If the vehicle is based on a car, it will usually have front-wheel drive. If it is based on a bakkie, it will have-rear wheel drive, and be lot tougher than the car-based version.
Two-wheel drive with automatic part-time 4WD: These vehicles are usually based on a car, and will be front-wheel-driven. The rear wheels will come into action automatically when the front wheels start to spin. This is by no means the ideal set-up because there are situations, such as in sand or mud, where you don’t want to come to stop and only then find you’re in 2WD.
Two-wheel-drive with manual part-time 4WD: This is a typical bakkie-based set-up, and it usually has a low-ratio transfer case as well. Usually there is no diff between the front and rear axles, so that the vehicle behaves like a 4×4 with a locked central differential.
Permanent 4WD without a low range transfer case: This is an excellent set-up if you don’t need two sets of ratios.
Permanent 4WD with a low range transfer case: This is the ideal set-up for serious off-road driving, and is often combined with three diff-locks.
My first choice would be an unboosted diesel engine. They have a reputation for lasting a long time, and deliver a good torque spread at low revs. Toyota Land Cruiser 70-Series models seem to be the only diesel vehicles that are still listed as not having turbocharged engines.
Petrol engines are my second choice. They tend to put up with more abuse than turbodiesels, and they often require less frequent servicing.
Most turbodiesels deliver exciting levels of torque. This allows them to cope brilliantly with off-road driving, but they have to be pampered. For example, if a petrol-engined vehicle crosses a stream, and the paper air-filter gets wet, it will result in a rich mixture, causing the engine to run cooler but use more fuel. If the same thing happens with a diesel-engined vehicle, the engine will get less air. This will cause overheating and could lead to engine failure.
Many off-road enthusiasts prefer a manual gearbox, because they like to feel in control. It also wastes less energy than the older kind of automatic gearboxes.
Modern automatics, especially the twin-clutch variety, do not waste energy, and can in many cases be operated in manual or automatic mode.
Constantly-variable transmissions (CVTs) are able to change to any ratio between a fixed low value and a fixed high value. They’re available in a few off-road vehicles but the jury is still out on whether they’re any good.
ADVANTAGES OF 4WD
Many people think that one can go anywhere with 4WD. This is simply not true, unless you have three diff-locks that force the wheels to rotate together. Even then one can get into a situation where there is so little traction that all four wheels simply spin and the vehicle doesn’t move.
The major advantage of 4WD is that each driven wheel gets only 25% of the available torque instead of 50%, making it a lot easier to control wheel spin. Many modern vehicles also control wheel spin by using the ABS unit to brake any wheel that rotates faster than the others.
DISADVANTAGES OF 4WD
They are more expensive to buy and maintain. Tyres are usually more expensive than road tyres as well.
In the more rugged vehicles, the transfer cases or the tyres make so much noise at freeway speeds that the journey becomes an endurance test. In contrast, soft-roaders (vehicles based on front wheel driven cars) are usually quiet at freeway speeds.