Manual v Automatic re: fuel economy

NIMAN

Generally which would be seen as being more economical in terms of fuel use?

Heroditas

NIMAN wrote: »

Generally which would be seen as being more economical in terms of fuel use?

Edited due to sheer stupidity on my behalf!

bazz26

There is no one size fits all answer to this. It depends on many factors including the car and type of gearbox fitted to it. Some auto boxes are more fuel efficient than manuals, some are not.

colm_mcm

A manual will almost always be more economical.
Some automated dual clutch manuals (as in not a cvt or torque converter) can be more economical, and some simple automated manuals (Toyota multimode for example) will be designed in such a way that theyll change gears at specific times to do well in emissions cycle testing. This doesn't translate to better real world economy but results in lower emissions than manual on paper and therefore lower tax.

Heroditas

Ummm, I misread this as a diesel v petrol debate.
Ignore what I posted!

Atlantic Dawn

I would say typically an automatic on a motorway run would be more fuel efficient than a manual, in the city I would say a manual would be.

djimi

Atlantic Dawn wrote: »

I would say typically an automatic on a motorway run would be more fuel efficient than a manual, in the city I would say a manual would be.

Out of curiosity, why would there be a difference between auto and manual on a motorway, when (assuming cruising) presumably both would just select a gear and stick to it?

Atlantic Dawn

djimi wrote: »

Out of curiosity, why would there be a difference between auto and manual on a motorway, when (assuming cruising) presumably both would just select a gear and stick to it?

Im assuming sticking it in cruise control for both manual and automatic, the automatic can run through the gears where the manual can't when cruise control is set. Same for if a manual and auto were both running at 120kph with cruise control not engaged the human in the manual car can't select the correct gears as good as the automatic can, assuming trying to keep the car at a constant 120kph.

Jesus.

When it comes to the average car, its always going to be manual.

corkgsxr

Atlantic Dawn wrote: »

Im assuming sticking it in cruise control for both manual and automatic, the automatic can run through the gears where the manual can't when cruise control is set. Same for if a manual and auto were both running at 120kph with cruise control not engaged the human in the manual car can't select the correct gears as good as the automatic can, assuming trying to keep the car at a constant 120kph.

Only affects it if on a very steep hill. Very rare.


A manual should be more efficient due to mechanical losses through the autobox which is why alot of manufacturers are using autos that are essentially manuals that the car changes gear instead of you

Cedrus

Jesus. wrote: »

When it comes to the average car, its always going to be manual.

Of course you'd need to factor in the average driver as well.
It's a lot harder to rev the sh!t out an automatic or spin the wheels, neither of which are fuel efficient.

rocky

DSG>manual>torque converter auto > cvt

Kopparberg Strawberry and Lime

Manual would be more economical if people knew how to drive them..... but they don't so people save more with automatics.

colm_mcm

Kopparberg Strawberry and Lime wrote: »

Manual would be more economical if people knew how to drive them..... but they don't so people save more with automatics.

I wouldn't go along with that tbh. You need to give people more credit.

mitosis

Much will depend on the age of the car

colm_mcm

mitosis wrote: »

Much will depend on the age of the car

As in how old tech the auto box is?

biko

Manual is somewhat more economical but to reject all automatic cars because of this is a fallacy. The drivers style of driving is the most important bit regarding fuel economy.

Seweryn

Atlantic Dawn wrote: »

I would say typically an automatic on a motorway run would be more fuel efficient than a manual, in the city I would say a manual would be.

It would normally be the other way round in case of a traditional torque converter type automatic transmission.

In general the manual version of the same car is about 20 to even 25% more fuel efficient than an equivalnt traditional type automatic gearbox equipped model.

The newer generation auto transmissions are almost as efficient as manual boxes and the automated DSG type transmissions are the same or a little more efficient, as the human factor plays its role in this case.

dharn

I would expect the bmw 8 speed autoboxes would be more economical than the 6 speed manual

biko

In a manual the driver shifts the gears. In an automatic the transmission has to do this work and the energy to do it has to come from the engine (as opposed to a person) and thus will use up a bit more fuel.

bucketybuck

In the truck industry, where fuel economy is king, there is a reason all manufacturers are moving to automatic gearboxes.

padd b1975

Automatics can be harder on brakes too.

SpaceTime

padd b1975 wrote: »

Automatics can be harder on brakes too.

But automatics aren't hard on the clutch

It all balances out!

I think driver behaviour is a huge factor though. I would like to see the comparison between your average clueless driver in both types of car.

billie1b

I own a manual car and automatic jeep, I drive economically and use cruise on both where possible, the auto jeep is far more economical than the car

Seweryn

billie1b wrote: »

I own a manual car and automatic jeep, I drive economically and use cruise on both where possible, the auto jeep is far more economical than the car

Yeah, the Jeeps are always more economical. That is why so many people drive them.

billie1b

Seweryn wrote: »

Yeah, the Jeeps are always more economical. That is why so many people drive them.

Well considering I have a wife, 4 kids and 2 dogs and drive between here and France all the time, its the only thing big enough to fit us all, believe it or not its not just used for a status or school run as people who dont have them like to believe

colm_mcm

billie1b wrote: »

I own a manual car and automatic jeep, I drive economically and use cruise on both where possible, the auto jeep is far more economical than the car

That's kinda comparing apples and oranges though.

billie1b

colm_mcm wrote: »

That's kinda comparing apples and oranges though.

Not really, I pay ten euro more to fill up the jeep and get 400 extra kilometres, it means its a lot more fuel efficient, even with a bigger engine

KwackerJack

The jeep may be better if the car is 2.0+

Or its a SUV rather than a full size 4x4

Seweryn

billie1b wrote: »

Not really, I pay ten euro more to fill up the jeep and get 400 extra kilometres, it means its a lot more fuel efficient, even with a bigger engine

It is not the point.

Get two same "jeeps" with the same engines, one with manual and the second one with an auto transmission. And then compare the fuel economy.

Otherwise, I can tell you millions of stories like yours in favour of any transmission.

colm_mcm

billie1b wrote: »

Not really, I pay ten euro more to fill up the jeep and get 400 extra kilometres, it means its a lot more fuel efficient, even with a bigger engine

Doesn't make it down to the gearbox though.

mitosis

billie1b wrote: »

Not really, I pay ten euro more to fill up the jeep and get 400 extra kilometres, it means its a lot more fuel efficient, even with a bigger engine

Are you saying you get 50mpg in a Jeep? The best the manufacturers claim is 30mpg.

EDIT: I now see it is not a jeep, but a Nissan. Please call it a Nissan. I don't call my bmw a merc.

billie1b

Seweryn wrote: »

It is not the point.

Get two same "jeeps" with the same engines, one with manual and the second one with an auto transmission. And then compare the fuel economy.

Otherwise, I can tell you millions of stories like yours in favour of any transmission.

The jeep is a full 4x4 Pathfinder, I had a 2005 one bought it in 2008, 5 seater, manual, was getting 550 - 600km per tank, in 2010 we had 1 extra baby and the 2 dogs, got a 2006 one, 7 seater, automatic full 4x4, gets between 750 - 850km
The car is a 2 litre diesel, manual, it does around 450km per tank

colm_mcm

Sounds like your car is broken, 280 miles out of a tank?
25mpg?

Jesus.

biko wrote: »

In a manual the driver shifts the gears. In an automatic the transmission has to do this work and the energy to do it has to come from the engine (as opposed to a person) and thus will use up a bit more fuel.

Is that why Americans tend to be quite fat?

Seweryn

billie1b wrote: »

The car is a 2 litre diesel, manual, it does around 450km per tank

Assuming the car has a 70l fuel tank, it does 18 mpg. This is about a third of what you should be getting, which means either the car is broken (fuel leak somwhere?) or is used on a half a mile trips to the shop and back in very hevy traffic. Still uncomparable to a trip across France in the jeep.

KwackerJack

Your car is on its last legs if your jeep is getting better mpg.

I've had all types of manual and auto jeeps and never got over 33mpg.....usually averaged 26 mpg.

Even if the car only does stop start and the jeep motorway you still would see better mpg from the car.

zzantara

There is a very simple and certain to compare the Fuel Economy of any Manual v Auto version of a particular model .
Compare the Emissions - simple as that.
Some Auto transmissions are actually "Manual transmissions that are changed automatically" and can be more fuel efficient as they are always in the correct gear ,also some auto versions have a six speed gearbox compared to a five speed manual.
The one "black and white way" to confirm Fuel Economy is to "check the emissions" and compare.

visual

I drive a Jeep Grand Cherokee auto it gussing fuel if it was manual I guess I get much better mpg as I change up sooner.

All the auto versions of cars I have driven have always faired worse than the manual

Mostly because the autos have less gears but also because the gear changes are at higher rev than what I would when driving easy.

Quick example my over drive comes on at 120kph if I had manual control over drive would be at 100kph.

I know newer autos have more gears but I would see auto 8 speed only equates to manual 6 speed.

I like autos better but not for mpg more for convenience especially in city traffic.

Jesus.

zzantara wrote: »

Some Auto transmissions are actually "Manual transmissions that are changed automatically"

Forgive my ignorance mate but what's the difference between what you've described and a 100%, fully automatic gearbox?

billie1b

mitosis wrote: »

Are you saying you get 50mpg in a Jeep? The best the manufacturers claim is 30mpg.

EDIT: I now see it is not a jeep, but a Nissan. Please call it a Nissan. I don't call my bmw a merc.

Sorry im one of the aul lads that refers to a 4x4 as a jeep

billie1b

Seweryn wrote: »

Assuming the car has a 70l fuel tank, it does 18 mpg. This is about a third of what you should be getting, which means either the car is broken (fuel leak somwhere?) or is used on a half a mile trips to the shop and back in very hevy traffic. Still uncomparable to a trip across France in the jeep.

The car is a passat, 2005, its the average for a passat, I know a lot of people with them, from 2008 and up they are a lot better on fuel, its in perfect working condition, no leaks or what not

Seweryn

billie1b wrote: »

The car is a passat, 2005, its the average for a passat, I know a lot of people with them, from 2008 and up they are a lot better on fuel, its in perfect working condition, no leaks or what not

How is it driven? What conditions, distances per each spin? All gears are being used?
There are no diesel engined Passat models from any generation that are normally that bad on fuel. You would get a better fuel economy out of a 5-litre petrol limusine if driven steady on open roads.

billie1b

Seweryn wrote: »

How is it driven? What conditions, distances per each spin? All gears are being used?
There are no diesel engined Passat models from any generation that are normally that bad on fuel. You would get a better fuel economy out of a 5-litre petrol limusine if driven steady on open roads.

25km each way to work on the N3 and M50, 50km in total 6 days a week, the other half uses the Nissan for the school runs, local shops and going shopping and when we all go out together. I drive it in a normal fashion, use all gears and rarely speed. My brother has the same car and a bloke in work and they both are averaging the same mileage

Jesus.

billie1b wrote: »

The car is a passat, 2005, its the average for a passat,

18 mpg is certainly not the average for a diesel Passat mate. There's definitely something wrong there.

Seweryn

billie1b wrote: »

25km each way to work on the N3 and M50, 50km in total 6 days a week, the other half uses the Nissan for the school runs, local shops and going shopping and when we all go out together. I drive it in a normal fashion, use all gears and rarely speed. My brother has the same car and a bloke in work and they both are averaging the same mileage

I can't believe you are getting 450km on a 70l tank assuming there is nothing wrong with the car. This is just madness. You should average about 1200km on a full tank, 450km is crazy low.

Your brother and your college are getting the same mpg between themself or same as yours?

billie1b

Jesus. wrote: »

18 mpg is certainly not the average for a diesel Passat mate. There's definitely something wrong there.

Sorry typo on my post, the car is a petrol not a diesel, the Nissan is the diesel and passat a petrol

jharr100

Seweryn wrote: »

I can't believe you are getting 450km on a 70l tank assuming there is nothing wrong with the car. This is just madness. You should average about 1200km on a full tank, 450km is crazy low.

Your brother and your college are getting the same mpg between themself or same as yours?

I've a 2004 diesel passat 130bhp and I average approx 1000km from a tank . 50-52 mpg.

Jesus.

billie1b wrote: »

25km each way to work on the N3 and M50

And its not even City driving? That's even closer to Motorway than Mixed driving.

The only thing I can think of is someone has bored a hole in your tank as some kind of practical joke.

billie1b

Seweryn wrote: »

I can't believe you are getting 450km on a 70l tank assuming there is nothing wrong with the car. This is just madness. You should average about 1200km on a full tank, 450km is crazy low.

Your brother and your college are getting the same mpg between themself or same as yours?

My brother and Matt from work both get the same, between 450 and 500km for a full tank. I kust always assumed it was average for them, my neighbour actoss the road has one and he told me his average is the same

Seweryn

billie1b wrote: »

Sorry typo on my post, the car is a petrol not a diesel, the Nissan is the diesel and passat a petrol

That changes things a bit, but I would still expect about 700km from the full tank. Easily!