Hello Paul, I have a big argument with my fellow drivers at the ministry where I work that cars with manual gearboxes have better fuel economy than those with automatic gearboxes. Please help us to determine the truth in this matter. Christopher.
Hello Christopher, in the past it used to be generally true that manual transmissions (gearboxes) were more fuel efficient or gave you more kilometres to a litre of fuel because they had more higher gears than the automatic transmissions. However, the evolution of the automatic transmission has made it equal or in some cases more fuel efficient than the manual one. While earlier manual transmissions had five gears, earlier automatic transmissions had only three or four gears. Higher gears (3,4,5 etc) make a car run lighter, which reduces the engine load and fuel consumption.
However, newer post 1995 and 2005 automatic transmissions have incorporated innovations such as overdrive facility and increased gears to catch up with or exceed the fuel economy of the manual transmission. There is a catch. You need to know how to use the overdrive facility to be able to reduce engine revolutions per minute at higher speeds to get the top up gear. You will only find automatic transmissions with 5, 6, 7 or 8 gears in newer post 2010 or brand new vehicles. You must have the budget for the newer cars to experience the superb fuel economy in newer automatic transmissions.
That not withstanding manual transmissions in newer cars have also stepped up their game by increasing the number of manual gears from the conventional 5 to 6 or 7 gears. So, there is no clear winner of your transmission fuel efficiency argument. Technology advancement and manufacturer’s design determine which transmission, automatic or manual, is more fuel efficient.