What is a Semi-Automatic Car?

Semi-Automatic Transmission Gearshift Stick; Close-up View Of Lever

Modern cars are usually split into two different types when it comes to the gearbox: automatic and manual. However, there is a third option available that most people probably aren’t aware of, it’s somewhere in between the two – a semi-automatic gearbox. But what is a semi-automatic car?

Most people will have heard of manual and automatic cars and would know the difference between the two. It’s simple, a manual gearbox requires the driver to change the gears themselves using a clutch and a gearbox, whereas, in an automatic car, the gears will change automatically based largely on the speed of the car, using computers built into the vehicle.

What is the difference between an automatic and semi-automatic transmission?

The main appeal of having a semi-automatic car is that the driver has the option to control the gears manually or automatically, whichever they prefer at the time. The use of electronic components in an automatic car can sometimes mean it struggles to complete gear changes smoothly (unless the car uses a dual-clutch transmission), but when you’re using a semi-automatic car, because the driver is controlling the gears manually, it can be just as smooth as driving a manual car (given that the driver is skilled and has experience driving a manual car).

How does a semi-automatic transmission work?

Just like any other type of transmission, a semi-automatic transmission takes kinetic energy produced from the engine that makes the wheels rotate, and the gears control how fast or slow the wheels spin. However, unlike a manual car which has a clutch pedal, a semi-automatic replaces this with a hydraulic motor, so the driver is not required to control the clutch with a foot pedal. The gear selector also looks very different from a manual gear stick. On a manual transmission, you’ll have the gear numbers laid out, in a fork-like arrangement that the driver will work through as the car changes speed. Whereas, on a semi-automatic transmission, you’re likely to see a lever with +/- symbols that replace the gear numbers (this is particularly true in modern semi-automatic cars.) As well as those symbols, you’re likely to see the letters P, R, N, D and M, or A, N, R and M.

N = Neutral

R = Reverse

M = Manual

P = Park

D = Drive

A = Automatic

Can I drive a semi-automatic car like an automatic?

The simple answer is yes. In most modern cars with a semi-automatic transmission, you can drive it exactly like you would in an automatic. The option to be able to change the gears manually is the reason most people choose a manual or a semi-automatic over a regular automatic. Although, if you want to drive an automatic car due to the convenience and simplicity, but still want to have the option to change the gears manually in certain situations like going up or downhill, then a semi-automatic transmission may be for you.

Can I drive semi-automatic car with an automatic licence?

Semi-automatic cars are regarded as automatic for driving test and licence purposes as there is no use of a clutch pedal. As long as the driver has an understanding of what speeds they’d need to change the gears at then it is perfectly safe and legal for a driver that does not have a manual transmission licence to drive a semi-automatic.

Can I stall a semi-automatic car?

You may think a semi-automatic car would be impossible to stall because it has no clutch pedal. In some circumstances, however, it is possible for this to happen. For example, if the car is motoring forward and the reverse gear is selected, it will cause the car to stall. It would be the same as if you were reversing and selected a forward gear, although these are very rare scenarios that are easily preventable.

How to drive a semi-automatic car

When driving a semi-automatic car, you have the option to drive it like a manual or an automatic. If you’re thinking of buying a semi-automatic car, you’re most likely thinking about using it primarily as an automatic due to the ease of driving. In this case, to drive the car, you would use the gear selector to choose “A” for automatic, or “D” for drive which will go through the gears automatically without requiring you to do anything other than accelerate, brake and turn the wheel. The great thing about owning a car with a semi-automatic transmission is that if you do happen to get bored of driving in automatic mode, you have the option to go through the gears yourself and have a bit more control over the car. Unlike a manual car though, the number of the gears aren’t laid out in the traditional way. You’ll see that there are + and – symbols to indicate when to move up and down the gears, to do this though you’ll need to make sure you’re in “M” (Manual) mode.

To reverse the car, simply put the gear stick into “R” like you would with an automatic or manual. And when the car has stopped, you’ll need to put the car into Neutral, this will stop the car from moving although you’ll still need to put the handbrake on.

WikiHow have a step-by-step guide on how to drive a semi-automatic car which may be helpful if you are still scratching your head.

What is a dual-clutch transmission?

A dual-clutch transmission is a type of automatic transmission that makes use of two clutches that work together, just like a semi-automatic transmission, there is no clutch pedal for the driver to use, which makes it automatic. One clutch will control the even gear numbers, whilst the other will control the odd numbers, this allows the gears to be changed without halting the power flow from the engine resulting in a much smoother transition between gear changes. In fact, it’s so smooth you most likely wouldn’t recognise when the gears change, this makes it very appealing to motorists that struggle with the sudden jolting that can sometimes happen when changing gears in a manual car.

Mandy Weston

Mandy Weston

Mandy is an ex-mechanic, with 22 years’ experience in the motor industry. As an in-house motoring expert, Mandy is the go-to woman for any relevant questions that our customers have; both garages and drivers. From specific problems with your car to general maintenance, Mandy is a reliable source of information and advice. Her passion for motoring is a huge factor to her success and the huge wealth of knowledge that she has. She now uses her remarkable grasp of the industry to write regular content for our readers to help drivers understand their car better, avoid being ripped off by garages and save money on their motoring requirements.

2 Replies to “What is a Semi-Automatic Car?”

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