Manual, AMT, Automatic: 6 Different Gearboxes Explained
Choosing the gearbox is as important as picking the right car. Making this choice was relatively easier in the past as just a couple of options were available back then. But today, multiple gearbox options are available, even on affordable cars. These differ sharply from each other in their nature and performance. Let's discuss them in detail so that you get better clarity on which one to pick for yourself.
This is the most common transmission type- the stick shift. Back in 2023, manual gearboxes had a share of 71-73% in the passenger vehicle space. In more recent times, automatics have gained ground, pushing the manual’s representation to around 70%. Manual gearboxes give the driver complete control over shifts and are often preferred by enthusiasts. Most cars and SUVs come with five-speed or six-speed manual transmissions. Four-speed boxes have become extinct.
The driver in this case operates the clutch himself and shifts gears manually. He/she enjoys maximum control over power delivery and engine rotations. It is good for highway-driving. Manuals are also less expensive than automatic boxes, and are easier to maintain. They often have significantly higher fuel efficiency figures than corresponding automatics.
These transmissions have one major disadvantage. They can be very tiring in bumper-to-bumper traffic, especially if the car has a tight clutch action. Cars and SUVs from some manufacturers come with clutch pedals that take effort to depress.
Are you a person who likes the control offered by manual transmissions but do not want to fiddle around with the clutch pedal every now and then? The iMT is for you! Think of it as a manual transmission with an automatic clutch action. There is no clutch pedal in this setup. The transmission uses sensors to mitigate shifting intent and actuators to automate the clutch operation. The driver just needs to shift gears manually.
iMT setups are much easier and more convenient to drive in cities than conventional manual gearboxes. It is also claimed to reduce pre-mature clutch wear. Korean giants like Hyundai and Kia offer this type of gearbox on models like the Venue, Creta, Carens etc.
Automatic transmissions are very convenient in modern driving conditions, and AMTs fake the end-effect using technology! It is essentially a manual gearbox in which both the clutch and shifting are controlled by electro-hydraulic actuators.
The system uses sensors to monitor vehicle speed, engine RPM and other variables. The Transmission Control Unit (TCU) processes data from these sensors to decide when to shift and to which gear. And finally, electro-hydraulic actuators move the clutch and perform the shifting, exactly like how a human would do.
The biggest advantage of AMTs is its cost effectiveness. They aren’t as expensive as conventional automatic transmissions, but deliver handsfree driving. More importantly, they deliver excellent fuel efficiency. Many budget-friendly cars use this transmission. Maruti Suzuki, Hyundai and Tata Motors use AMTs on multiple affordable models.
Maruti Suzuki was, in fact, the first company to introduce this transmission type in India. The Celerio was the first car to be equipped with AMT, in 2014. Over the years, Maruti Suzuki has made significant improvements to the AMT setup. Earlier iterations lacked refinement and had a pronounced ‘head nod’ and slow, jerky shifts.
Maruti Suzuki almost perfected the technology over time. The AMT setups on modern Maruti cars are much smoother and offer faster shifts under hard acceleration. The outgoing Maruti Baleno is a good example.
Hyundai’s AMT transmission, found on models like the Grand i10 NIOS, Aura and Exter, is often appreciated for its smooth shifts and sharp performance. There is little to no ‘head nod’ in it. Tata Motors uses AMT boxes in models like the Tiago and Punch. While they aren’t as smooth as the Hyundais, these too are in good demand.
These are the true old-school automatics. A torque converter automatic transmission is also one of the most reliable. It uses a hydraulic fluid coupling instead of a physical clutch. This consists of an impeller and a turbine. The shifts in this case are very smooth.
Torque converter automatic transmissions are usually found on cars and SUVs with bigger engines. They offer plenty of low-end torque and a strong mid-range. On the downside, these gearboxes usually have relative lower fuel efficiencies due to transmission losses and the heavier setup. In India, a lot of cars and SUVs feature torque converter automatic boxes.
From small SUVs like Skoda Kylaq to big, butch full-size SUVs like the MG Majestor, many come with AT boxes. 6-speed AT is the most common while some models also get 8-speed units.
This automatic transmission is for performance seekers, as it offers extremely fast shifts. This setup uses two separate clutches- one for odd gears and one for even. This facilitates quick and seamless shifts. Power losses are also minimal in this case.
Today, we have both dry and wet clutch DCTs. The latter excels with its thermal management. These transmissions could potentially overheat in long bumper-to-bumper drives. The recently-launched Renault Duster features a wet-clutch DCT, while those from Hyundai and Kia are dry clutch units.
DCTs are fun to drive, but are equally complex. This makes repairs expensive and time-consuming.
Volkswagen calls their DCT transmission technology DSG- Direct-Shift Gearbox. It is found on models like the Virtus, Taigun, Tiguan, Tayron and others. The same is used on Skoda models as well.
This transmission is for drivers seeking a laid back, and smooth drive. CVTs lack physical gears, and use a belt-and-pulley system instead. This essentually means infinite gear ratios and a smooth and seamless driving experience. This is also the quietest and most refined of all automatics. It also offers good fuel efficiency under gentle driving.