Should you buy an all-wheel drive family car?
The all-wheel drive fad
The option to buy an all-wheel drive is in virtually every popular vehicle model today and it’s very enticing.
We’re told by car brands that all-wheel drive is the drivetrain to have, offering superior road-holding compared with conventional front-wheel or rear-wheel drive vehicles.
But how true is that claim and does it actually matter, or even apply, to you, the consumer, and your circumstances? How would you know when you’re always being told AWD is the thing to have?
I’m going to help you separate fact from furphy, so that you can potentially save some money and still end up buying a very safe vehicle capable of performing well at all the tasks you’re likely to throw at your next new family car.
Let's start by understanding exactly what all-wheel drive actually is, and help you figure out if you need it.
How does tyre grip work?
Firstly, all-wheel drive is sold as some kind of iron grip system for the road in all conditions, adding stability and gold-standard traction. It doesn’t.
Put very simply, you need each little block of rubber tread on your tyre to interlock with the road surface, in order to have traction.
Traction is the ability for the rubber to interlock and the wheel to turn without breaking that lock.
Grip is the actual lock of each section of rubber. And friction is the physical touching of the rubber to the road.
If you wanna get technical, learn how tyre grip and friction works here_
Rubber, under weight, conforms to the road surface, which creates an interlocking between the road and tyre - this is what ‘grip’ is. Hence unweighted tyres don’t grip very well (and why loading your trailer correctly when towing is important).
When you apply throttle, the wheel turns at a very rapid rate, and the vehicle goes forward because of that grip. Too much power and that grip is broken; this is wheelspin. Kinds like how your kid’s fingers grip the monkey bars using their skin.
What AWD does is divide the available power. It’s split between four tyres, 25 per cent each, not 50 per cent, to each front or rear wheel.
One quarter the amount of power going through each tyre, reduces likelihood of wheelspin because less power is trying to unlock that grip between tyre and road. Add water to this equation and the results are even more profound between two-wheel drive and all-wheel drive. Ask anybody who goes regional camping or light off-roading/soft-roading.
Even some old sealed roads can be especially slippery when wet, especially after long periods of hot weather are broken by heavy rains which carry the once-sticky now lubricating oils and tar from the road surface onto your tyres. Stopping at traffic lights on slopes, together with rain, can cause wheelspin and often you’ll hear and feel the vehicle’s electronic safety aids kick-in to cut power to the wheels and deaden the throttle to stop the wheels from slipping.
Do you actually need AWD?
When driving on dry dirt or gravel roads, you’ve got four contact patches gripping the road with a more conservative amount of power feeding from the engine. So, if you lose grip on, say, the front left, the system will send power to the three gripped-up wheels and cut power to the spinning one.
If you’re in the middle of an often blind, narrow, gravel road frequently because you perhaps live in a regional area - and 2/3 of Australian roads are unsealed - you can find yourself having to make split-second swerving manoeuvres for oncoming log trucks or big 4WDs, sometimes trail bike riders will cut blind corners, or perhaps a furry old mate hops out from behind the ferns for a quick cuddle.
On the other hand, if there’s a chance you’ll find yourself crawling through more soggy conditions, like heavily rain-soaked dirt roads, like those often found en route to popular camp grounds in the mountains where you get a series of hairpin turns, need acceleration out of these slow tight turns; if wet, this can be too much for two-wheel drives. Why? Because 50 per cent of the power is turning each front or rear wheel, which is clearly too much for the available level of grip.
However, if you split that power again, you only have 25 per cent going to all four wheels, increasing the likelihood you’ll actually get out of that sloppy steep climb.
This situation might happen on steep, mossy or leafy driveways after it rains. Some suburban streets in metro areas rarely get sunlight on the bitumen, so they stay slippery because there’s a constant tree canopy over them; not ideal for a front-wheel drive or rear-wheel drive. Ice-prone roads in wet, cold winters can be more safe to traverse with an AWD system.
TOWING
Pulling boat trailers up out of slippery boat ramps can be done much easier with AWD, again because you reduce the chance of wheelspin by overwhelming the available tyre grip. And driving into and out of steep slippery driveways with a campervan or box trailer will also be less fraught thanks to AWD.
But that’s about where the advantages end. You don’t really gain much else when driving normally, other than slightly altering the very technical dynamics of how the vehicle drives.
Driving on flat, dry, sealed roads doesn’t need AWD, and nor does conservative driving on good quality dirt roads, strictly speaking, if you know how to keep your momentum and drive carefully. When you apply too much power on slippery roads, you can create a trench-digging effect with the front wheels ahead of the driving rear wheels (using a ute as an example, obviously). This can lead to progressive micro-moments of wheel slip where, if you don’t get to the top of a gradual slope early enough, you can end up digging the rears in and getting stuck. In these kinds of situations, high-4 (AKA ‘4H’) can keep you out of the trenches, or at least reducing that wheel slip phenomenon.
You have to assess the likelihood of getting into those precarious situations while towing. If you’re a tradie, it’s highly likely you’re going to be parked on a sloped street or steep driveway covered in lose gravel or slippery bricks - possibly even with a tool trailer behind - in which case having AWD will be a benefit, especially if you then take your ute off-road or camping on weekends. If you have a small tinnie which only sees your local modern, high quality, grippy boatramp, you probably don’t need AWD. If it’s a big boat you take everywhere on touring holidays several times a year, where the quality of boatramp will be largely unknown, AWD could be very useful.
Why you don’t need AWD
Stability control, traction control, limited slip differentials and throttle management technology all help a regular rear-drive or front-drive through many situations AWD is purported to 'help’.
Driving along normally on dry roads, which is arguably the vast majority of the driving you’re ever gonna do, doesn’t need AWD. And if it does, those traction aids will most likely save you. Or you can probably cure the problem with momentum or simply choosing a different path, if things get dire. (Yes, exceptions to this will exist.)
Notice how there isn’t a spate of tiny little gutless front-wheel drive hatchbacks all getting stuck out there in regular traffic? They seem to do just fine without AWD. Without turning all the mandatory safety features off, try generating wheelspin in a Kia Cerato or Mazda 3. Hell, try doing it in a big Nissan Patrol. Actually, no, don’t do that.
Anyway, you can’t, really. So AWD is only really relevant if you expect to have those dodgy driving scenarios in your future. Do you have friends who live in, say, Lane Cove or on the side of a mountain?
Not every AWD system is the same
There are a few different kinds of all-wheel drive systems offering varying levels of performance.
There's the constant AWD drivetrain of, most notably, all Subaru family vehicles (Outback_, Forester_, Impreza_), excluding BRZ. This system splits available power to all four wheels all the time. It's always turning all four wheels at the same time. There’s also a special coupling which stops the system breaking due to a condition called ‘wind up’, which typically happens on 4WD vehicles driving on high traction surfaces like bitumen and good quality dirt roads.
Then there is the ‘on-demand’ kind of AWD, which uses a computer to constantly listen to the front wheels for wheelspin. When it detects slip, the computer diverts power to the rear to assist, and may restrict power to the spinning wheels momentarily. This is good in most situations, and means you’re not needlessly in AWD when you don’t require it. But this system is reactive and can be tricked or kick in too late in some hairy situations like ice and snow, or to avoid digging up people’s driveways. Vehicles include Toyota RAV4_, the Mazda CX-5_ and the CX-9 seven-seater, and most of the small SUVs like Kia Seltos_, Hyundai Kona, CX-3 etc.
Then there’s the active on-demand system which is always feeding some form of power to the rear, despite being predominantly front-wheel drive. This is an excellent middle ground when it comes to efficiency and practicality. Vehicles include Hyundai Santa Fe_ and Palisade, and Kia Sorento, both with very proactive, constantly on-tap AWD systems.
There is also ‘four-wheel drive’ which means each of the four wheel turns independently of the others. This is better suited to longer-term, frequent off-road use, rather than occasional dirt roads which is perfectly okay to drive on with normal tyres and a normal rear-drive, front-drive or passive AWD system. If you were a tradie who spends every second day on muddy housing estates, then a low-range 4WD drivetrain is going to be much better suited. Vehicles include Mitsubishi Pajero Sport_ and Triton_, Nissan Patrol_ and most other utes. Oh, and, I guess, if you’re desperate, the Suzuki Jimny_.
It’s important to think about how you’re going to use your next new car and ask whether you’re likely to ever actually need AWD. It’s quite possible you might want to have it for those rare occasions, which is quite okay, but you need to make some allowances for living with an AWD, such as…
WEAR & TEAR
Four wheels driving the vehicle at all times, or at least sometimes, means you’re going to notice greater wear and tear on the tyres, but only after a long period of time.
Typically, a front-wheel drive will wear out the front wheels earliest because they’re doing all the steering, braking and accelerating. It’s similar for old-school rear-wheel drives, where the rear tyres would go bald slightly earlier than front tyres, generally speaking, but for AWD vehicles this is less of a problem.
With all-wheel drives, it’s usually pretty even between front and rear tyre wear, due to the divided workload each set has to cope with. What this means is having to replace four tyres at the same time, which can be expensive all at once, but it’ll take a longer time period to wear them out. Remember, this is why you need to rotate your tyres regularly on any vehicle, regardless of front, rear or all wheels being driven - so you don’t end up replacing two at a time and having oddly worn and unworn tyres.
Also worth keeping in mind, is the fact there are more driveline components in an AWD, particularly a mechanical system, which means potentially more parts to wear out and replace, or possibly break. But, again, if you drive carefully and conservatively, and have your vehicle serviced routinely, this shouldn’t be a huge issue - remembering, of course, that parts wear out on all vehicles, regardless of being AWD. What matters is how you treat the vehicle and keep on top of regular care.
The greater mechanical sympathy you have for your AWD vehicle, the longer it will last you and the fewer issues you’ll have - as well as the stronger your legs will be to stand on if there is an anamonic failure. If she’s clean and tidy and cared for (serviced as stipulated in the handbook by the manufacturer), the easier it’s going to be if you have a warranty claim to make in the rare event of something breaking. It also helps if you buy from a brand that looks after customers as its top priority.
Conclusion
Buying an all-wheel drive vehicle is becoming increasingly popular in new car purchases.
But for many people, it can be confronting trying to get the most in their next new car, while also balancing a budget. Money makes buying a new car hard, and as carmakers feature AWD into their products’ model ranges, that inflates the price.
You might want certain features in a second or third tier model grade, but often it won’t allow you any other choice than to have AWD - which can be more expensive, and sometimes it’s unnecessary to have it.
Those of you with a firm budget should try to see if you can live with a base model or whichever poverty pack is on offer, otherwise it’ll be up to your negotiating skills to leverage the dealership into saving you a few grand because you’re forced to buy the AWD instead of a stock FWD. It’s worth a try, but ONLY when you’re actually ready to buy, having done your extensive homework on which make and model you’re going for. And remember, there are other dealerships with that same vehicle - one sales guy refusing to budge because you wanna save cash by buying the non-AWD version doesn’t mean you can’t try the next suburb over, or even on the other side of town.
All-wheel drive is going to be beneficial to those who will need it. Now that we’re all out of lockdown, be realistic with your future prospects and where you intend to take your next new family car. Don’t pay more for AWD based on your dreams and fantasies of heading into the bush or driving across some remote, white sand beach with pale blue water greeting you with a lovely golden sunset - especially if you’re only going to the shops, school and the cheapest Big4 you can find.
If you have any questions about buying your next new AWD family vehicle, click the red button below and ask me anything - I’ll be happy to help and even get you a discount on it.