Geared: Pros/Cons of modern car transmissions
What transmission is in your car?
You hear these abbreviations a lot when people talk about their cars or while picking one, and the more letters it has, the more sophisticated it sounds.
But do you know what happens in an MT or AT? What’s an AMT? And why don’t CVTs have gears?
We pry open these gearboxes to give you an idea of the kind of engineering that went on to create an intermediary that allows your engine to deliver different levels of power to the drive wheels to suit just about any driving condition.
Is one really better than the other? Well, read on and decide which one fits your driving style and preference best.
Manual Transmission (MT)
Known as the manual, stick, or stick shift, this is the oldest and most classic form of transmission available today.
It uses a three-pedal system with a clutch on the left to engage and disengage the flywheel from the engine. It takes power from the crankshaft, which it then converts into varying speeds using the gear lever by the driver’s side, and then sends to the drive wheels to move the vehicle.
Because it generally has no electronic systems (there are some exceptions, e.g. auto rev-matching) the manual isn’t as costly (i.e. models with manual transmissions are entry grad models) and is cheaper to fix and maintain. If driven properly, it still delivers the best mix of engine response and fuel economy.
Not too long ago, it was the most popular gearbox. Now, it accounts for less than 40% of vehicles sold around the world so it’s not a surprise that there are many young drivers who don’t know how to drive stick.
PLUS
> Vehicles with a manual tranny are more affordable
> Little power loss in the system
> Potentially more fuel-efficient
> Simple to maintain
> Quicker response and acceleration
MINUS
> Comes with a steeper learning curve
> Can make driving in heavy traffic difficult
Automatic Transmission (AT)
This is what young drivers use now and what might become the most common transmission option in the future. You can tell a car is automatic if it only has two pedals and a gear lever that only moves forward and backward. But this is where it gets confusing: not all two-pedal cars are automatic because CVTs and DCTs/AMTs also just have two pedals.
What makes an automatic different is the use of a torque converter that's filled with fluid. Instead of a clutch, an automatic uses hydraulic fluid to transfer the power to the gears and drive the car.
The operation is a lot more complicated than it sounds, even more so when you watch it in a YouTube 3D video, but it couldn’t be simpler for the driver – just select D and off you go. As it’s an intricate multipart system that needs precise timing and movement, so many things can go wrong and if it does, expect a hefty repair bill.
It was also considered less fuel-efficient because of the energy loss of the hydraulic system to make the shifts smooth. Modern technology and the fact that it’s now running more gears has greatly reduced consumption though.
PLUS
> Simpler to drive
> Makes it easier to tackle inclines
> Smoother drive
> Easier to use in traffic
MINUS
> More expensive to maintain
> Reduced fuel economy
Continuously Variable Transmission (CVT)
This type of AT generally doesn’t use any gears. It is essentially a pulley, a belt, and a couple of cones. These are governed by the transmission control unit that adjusts the width and diameter of the pulleys in order to find the optimal ratio for the drive. So, it goes without saying that there is technically no limit to the number of forward gears in a CVT as it constantly changes ratios to match engine speed and power to the drive wheels.
No gears to lock on to means the whole process is very smooth and as it always keeps the revs low, it’s also very fuel-efficient. But purists will complain that without the sensation that gear shifting brings, it lacks the oomph that comes along with a perfectly-timed shift. The sound of the transmission is different too.
There's a new development called an e-CVT which ditches the belts and/or chains, and uses motors/generators to control the speed of the gearset components to get the optimal ratio. Basically, it simulates the behavior of a CVT.
It has a very basic setup, which means it doesn’t break easily but if it does, repairs are unlikely as it would probably require replacement. Let us know in the comments if that has been the case for you.
PLUS
> Lighter than similarly sized MT or AT
> Provides very smooth transitions
> Potentially the most fuel-efficient
MINUS
> Expensive to replace
> Dull and delayed feedback
Automated Manual Transmission (AMT)
Dual Clutch Transmission (DCT)
This type of transmission technology has been touted as the best of both worlds: the convenience of an automatic with the efficiency and performance of a manual.
It’s a manual transmission underneath that uses a computer and solenoids and doesn’t have a clutch pedal. It uses electronics to simulate a driver's left foot. Its straightforward design and operation make it an affordable gearbox for mass-market vehicles, but the driver should lift off the accelerator for that moment when the transmission shifts a gear (as you would in a manual) because there is no power to the drive wheels.
It must be noted that the dual-clutch transmission (DCT) is actually an evolution of the AMT. Also known as a twin-clutch transmission, the DCT is mechanically similar to an automated manual in operation but has two internal clutches and two gear sets. The odd (1, 3, 5, 7) gears are on one set while the even (2, 4, 6, R) gears are on the other, and each set has its own clutch. The computer, hydraulics, and solenoids control everything, although the driver can override it using paddle shifters. Depending on the drive, it preps the next gear so shifting is lightning quick and there’s no loss of power/torque. It’s more popular in high-performance vehicles.
Due to its complexity, it can have some reliability issues and can be expensive to maintain. There have been examples in the past of problematic DCT transmissions.
PLUS
> Manual-like efficiency
> Drives like an automatic transmission
> Simple and low-cost setup (AMT)
> Eliminates shift shock (DCT)
> Super-fast shifts (DCT)
> No loss of power or torque (DCT)
MINUS
> Takes getting used to
> Shifting can be awkward uphill
> Best with hill hold control/hill-start assist
> Complicated setup (DCT)
> Can be problematic (DCT)
There isn’t a right or wrong transmission. It all depends on your usage, preference, and to a certain extent, budget.
Sports cars will often use the highly complex DCT because it gets the most out of the high-performance engine.
AMTs are not as common in the Philippine market, but you'd normally find these on mass-market models because of the cost, maintenance, robustness (of some), and potential fuel efficiency.
Many models will get a CVT because of the transmission's fuel efficiency and the many technological advances that have improved reliability over the years. CVTs have largely supplanted older 4-speed automatics in the market.
Automatic transmission was the standard, but its market share is declining. In 2020, it only had a 28.72% share compared to 34.4% in 2015. The reason is that many automakers are shifting CVTs.
The manual transmission may be making a comeback. Experts predict its share in the market to hit 36.1% by 2025. In fact, as of last year, more than 80% of the vehicles sold in Europe were MT, but that was in Europe; traffic here is a different matter.
Whichever you choose, know that just like the MT, all transmissions require a certain amount of skill to get the most out of it. You can’t just jump in with a golem’s foot and expect smooth sailing.
Remember, always step gently, and floor it only when you really need it.
