Manual vs automatic – which is more fuel-efficient

In the past, manual transmissions were known to get better fuel economy than their automatic counterparts – which, in the early days, could use up to 10% more fuel than their manual equivalent. However, modern developments in automatic transmissions and variations have meant that this may no longer be the case.

According to Suzuki Auto South Africa, early introductions of automatics came with a three-speed automatic transmission which meant fuel efficiency suffered.

“This was because automatics used a viscous, fluid coupling, which allows the transmission to ‘slip’ when stopping, to prevent the car from stalling. But that same fluid coupling that allows the transmission to slip at low speeds was harming fuel efficiency at higher speeds,” said Suzuki.

While in contrast, with a manual transmission, the driver simply depresses the clutch, selects a gear and then releases the clutch. The car remains ‘locked’ in that gear until the driver physically changes to another gear.

However, as modern automatics gained additional gears – such as six, eight or even 10-speed setups you get now – the debate on fuel efficiency between manuals and automatics has become much more contested.

Suzuki said this is due to modern automatic transmissions having more forward gears than manual transmissions. Those extra gears help the engine deliver the same power to the wheels while working at a lower engine speed, which saves fuel.

Manual vs AMT

Among the technological advancements of automatic transmissions came the automated manual transmission (AMT). Suzuki said this is sometimes called a semi-automatic gearbox because it marries the clutch and gears of a manual with a set of actuators, sensors, processors and pneumatics.

Using an AMT system, the driver does not have to do anything, as the system operates the clutch and selects the right gear for the driving situation – although the driver can elect to use the gears manually.

“While operating like an automatic, on paper, an AMT gearbox offers the same fuel-saving benefits as a traditional ‘stick shift’ transmission,” said Suzuki.

However, the ultimate decider on which transmission offers better fuel consumption depends on how an individual drives their car.

If you drive a manual and keep the car in gear at a traffic light, riding the clutch to prevent rolling backwards or forwards, your fuel consumption will suffer, said Suzuki. Equally, holding it in gear until maximum revs just because it sounds good will hammer those fuel figures – including rapid acceleration followed by hard braking is also harsh on consumption and your car, the manufacturer added.

This is where the AMT could be better than a manual, as it takes away some of those bad driving habits. Additionally, even if you are a much more conservative driver, the automatic can make gear changes faster and more efficiently than you can with a manual shift.

As an additional fuel-saving tip, Suzuki said not to deactivate the auto Stop/Start if your vehicle has that option fitted, as it uses less fuel than when the engine is idling.

“Modern automatic transmissions have come a long way since their first introduction to motorists and can deliver the same fuel economy as a manual, if not better,” said Suzuki.

Source: Business Tech