Automatic gearboxes - everything you need to know
Car makers offer a baffling array of automatic gearboxes these days. Fortunately, we can help you tell your CVT from your DSG...
Automatic gearboxes aren’t exactly new. In fact, it could be argued that the very first production car, the 1886 Benz Patent Motorwagen, had one; it certainly didn’t have a clutch pedal. What’s certain, though, is that they’re now offered in any kind of car you could mention.
In fact, cars with automatic gearboxes are now outselling manual models. And with electric and hybrid cars making up many of the best sellers, it’s evident that the automatic takeover is only just getting started.
There are other reasons why car makers are falling out of love with manual gearboxes. They cost a lot to develop at a time when demand is diminishing, and they are no longer necessarily greener or more fuel-efficient than automatics – partly because the latter can be controlled by computer to change gear at precisely the right time to achieve the best economy and lowest emissions.
But while every automatic gearbox does basically the same thing, there is a baffling array of different types. And with manufacturers dreaming up brand names for their own particular offerings, it’s becoming rather confusing to work out what’s what. So, read on for our guide to the mysterious world of effort-free cog-swapping.
Torque converter automatic
Also known as Geartronic, G-Tronic, Steptronic, Tiptronic, ZF 8-speed
For Reliable and time-proven; usually smooth and quiet
Against Not particularly efficient; can be sluggish; sometimes pricey to buy
This is the traditional automatic gearbox that you would have found in pretty much every car without a clutch pedal 30 years ago. And it’s still very common today, particularly in executive and luxury cars, such as the BMW 7 Series as well as many larger SUVs.
The term ‘torque converter’ refers to the component that transmits power from the engine to the gearbox itself – like the clutch does in a manual car. But rather than having an actual, physical connection, as is the case with a clutch, the torque converter uses thick hydraulic fluid to transfer drive from the engine to the gearbox. It’s this fluid link that enables torque converter automatic set-ups to change gear smoothly.
This technology has been around for long enough to have been made very dependable. The downside is that the torque converter isn’t actually a very efficient way of transferring the engine’s power. As a result, this type of gearbox can be a little heavier on fuel than others, and the way it operates can give rise to tardy gearchanges.
You can still take control yourself, though; many systems provide the option to select gears manually, either using the gear selector or paddles behind the steering wheel. However, you’re rarely acting on the gearbox directly; you’re just giving it an electronic command. Some are more immediately obedient than others, but they mostly do what you ask.
Also known as Direct-shift gearbox (DSG), dual-clutch transmission (DCT), PowerShift, S tronic, Porsche-Doppelkupplungsgetriebe (PDK)
For Very quick to change gear; quite fuel efficient
Against Can be jerky in use; mechanical complexity can make repairs expensive
Dual-clutch automatic gearboxes began to appear in road cars in 2003, notably in the Audi TT and Volkswagen Golf R32, and can now be found in all classes of cars, from small hatchbacks such as the Volkswagen Polo to the likes of the Porsche 911 sports car.
In fact, a growing number of new cars are available only with a dual-clutch ’box, including the mild hybrid versions of the Seat Leon and Volkswagen Golf. Part of the reason is that they’re very efficient. However, they’re also very complicated.
It's worth noting that while most car models with DSG gearboxes will come with gearshift paddles behind their steering wheels, this isn't standard equipment on all models. On some Volkswagen Group cars, including the Skoda Karoq, you have to add paddle shifters as an optional extra when the car is ordered from the factory. On cars without paddle shifters you can still change gears manually by tapping the gear lever backwards and forwards, but if you want the ability to shift gears via paddle shifters it's worth checking if they are included as standard.
The DSG gearbox works on a similar principle to a single-clutch automated manual (more about which later) but, as the name suggests, use two clutches. The idea is that they can line up the gear they think you’re going to need next on one clutch while the other is still being used to drive the car, and this enables extremely quick gearchanges.
However, because of how they work, dual-clutch automatics tend to be jerkier than torque converter units at lower speeds. They can also be a bit too keen to get into the higher gears quickly, leaving the car in the wrong gear to provide the best acceleration for overtaking. However, to help counter this, most also allow the driver to change gear manually, often with shift paddles behind the car’s steering wheel.
Their complexity is another downside; in recent years, older units have gained a reputation for poor reliability and some owners have reported theirs as needing costly repair work.
Also known as e-CVT, Xtronic
For Mechanically simple and reliable; fuel efficient
Against Tends to be noisy; can be sluggish; little scope for manual control
The continuously variable transmission (CVT) is unusual in that it doesn’t use a series of cogs for gears like a traditional gearbox. Instead, it works a bit like the gears on your bicycle.
Inside a CVT gearbox you’ll find two cone-shaped pulleys – one connected to the engine and the other driving the wheels, linked by a belt. The pulleys expand and contract in diameter continuously as you accelerate or decelerate, and that alters the gear ratio.
Because the gearing is adjusted infinitely between the highest and lowest ratio, the engine is kept in its power band when you accelerate, rather than dropping in and out of the engine’s most efficient rev range, as is the case with other types of gearbox. What’s more, because there are no fixed gears, there are no gearchanges – and that means smooth acceleration without any jolts.
However, the downside is that, because the engine is held at peak power as you accelerate (normally at higher revs), CVT gearboxes can make cars rather noisy, especially if the engine is a bit weedy and needs to be revved harder to pull you along.
Toyota uses a more sophisticated gearbox, called e-CVT, in the Prius hatchback and RAV4 SUV, that replaces the belt and pulleys with two electric motor-generators. One is used to start the engine and act as a generator to charge the hybrid battery, while the other acts as a drive motor on its own or in conjunction with the engine. The system also enables the car to be driven in pure electric mode by mechanically decoupling the petrol engine.
Also known as Automated shift gearbox (ASG), EAT, EGC, ETG, robotised manual
For Inexpensive to buy; simple to produce; fuel efficient Against Tends to be jerky when changing gear;
often hesitant to respond
An automated manual gearbox is exactly what its name suggests, but you won’t find a clutch pedal and gearlever moving themselves around as if by magic. In fact, in most cases the gear selector looks just like a normal automatic’s, and there’s no clutch pedal at all.
Under the skin, though, this gearbox works much like a manual, but with an electronic control unit deciding when to change gear, rather than the driver calling the shots. When the computer decides that the time is right, it disengages the clutch automatically, selects a new gear and then re-engages the clutch.
The technology became popular in the late 1990s in performance cars, with Alfa Romeo, BMW and even Ferrari offering automated manual gearboxes. However, while they could shift gears quickly, they seldom did so smoothly. Plus, in less sporty cars, this type of gearbox is often either slow to change gear, jerky or, in the worst cases, both.
It’s no surprise that they were largely usurped by the dual-clutch automatic systems we explained earlier. However, automated manual gearboxes are still found in some new cars today, including the Hyundai i10, Kia Picanto and Toyota Aygo city cars. In these, the comparative lightness of this gearbox design is a significant virtue, contributing towards impressive fuel efficiency.
They’re also inexpensive to develop, in a market where profit margins are thin, and this means automatic cars can be sold for less than would be the case if they were fitted with a traditional torque converter automatic gearbox.
For The most direct and efficient way to send power to the wheels Against Only suitable for use in electric cars
We mentioned the first ever car in the intro, and now we’ve gone full circle; like the single-speed Benz from 1886, today’s electric, such as the Tesla Model 3, cars don’t usually have multi-speed gearboxes.
And for good reason. Electric motors produce all their torque (the turning or twisting force that gets you moving) from the moment you press the accelerator pedal. Petrol and diesel engines, meanwhile, develop theirs in a narrower band and have to be worked to develop it. So, like a cyclist, they need low gears to start moving or to get up a steep hill.
And because electric motors are capable of turning much faster than internal combustion engines (typically, at up to 20,000rpm, compared with a petrol engine’s limit of around 6500rpm), a single gear can take an electric car from zero to maximum speed, while a petrol or diesel needs many gears to do the same.
Ideally, that gear will strike a good balance between acceleration and top speed. If its ratio is too low, the car will accelerate very quickly but have a limited top speed. If the gearing is too high, it’ll reach a higher top speed but take longer to achieve it.
However, while single-speed gearboxes are simpler and easier to produce than multi-geared systems, making them cheaper to produce and maintain, not all electric cars use them.
The Audi E-tron GT and Porsche Taycan use a two-speed unit on their rear motor, with a low first gear and a high second gear. As a result, both cars have phenomenal acceleration yet are very energy efficient when running for sustained periods at high speeds.
Your automatic gearbox questions answered
Does having an automatic gearbox affect my car’s resale value?
Cars with automatic gearboxes tend to be more expensive to buy new than manual models, and they tend to retain that extra value secondhand, especially in classes where such gearboxes are relatively rare or where an auto ’box is expected. So, with manual gearboxes more commonplace in small cars, automatics can command a premium. Conversely, most luxury cars are bought with automatic gearboxes, and those with manuals are likely to be less appealing to buyers of used examples.
Should I take my driving test in an automatic?
You can take your driving test in an auto, but you’ll only be legally entitled to drive a car with this gearbox unless you retake the test in a manual car. It’s also worth knowing that car insurance for people with an automatic- only licence costs around a fifth more each year than it does for manual gearbox licence holders. As electric and hybrid cars become more common over the next five to 10 years, however, this price difference is likely to shrink.
Which is more durable: an automatic or manual gearbox?
Overall, both types of gearbox are broadly similar for the cost of repairs. There have been cases of cars with dual-clutch gearboxes suffering costly faults, but with automatic gearboxes that change gears instead of the driver doing so, there’s less scope for issues caused by wear and tear. Cars with manual gearboxes might require occasional clutch replacement, and many automatic gearboxes will need their transmission fluid changed; both of these can be expensive jobs.
Will manual gearboxes be phased out?
Some car makers have already dropped manual gearboxes from some models. Earlier this year, Mercedes-Benz announced that it is stopping the production of manuals as part of a cost-cutting initiative. As the 2030 ban on the sale of new non-electric cars in the UK approaches, we expect other brands to follow suit in slimming down their engine and gearbox line-ups, eventually leaving automatic gearboxes as the only choice on new cars.
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