Automatic gearboxes - everything you need to know
Automatic gearboxes vary widely in design and performance, and knowing what type your car has can be tricky. We’re here to help you tell your CVT from your DSG...
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.
For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here
Page 2 of 2