How much thirstier are automatics than manuals?

blobert

Hi there,

I know that you can get better fuel economy out of a manual than an automatic car but does anyone know how much (a rough idea of the percentage)?

Due to my work I've been doing a lot of city centre driving recently and I'm getting very sick of driving a manual all day. I know a lot of taxi drivers drive automatics, otherwise they'd have a sore left leg I'd imagine.

Fuel economy is important to me so like I said I'm just wondering how much worse that is likely to be for the sake of comfort in an automatic.

Any advise would be much appreciated.

mike65

Don't worry about the loss its just a few %, you'll waste more with soft tyres and a full boot.

Mike.

Wishbone Ash

It depends on the size of the engine - the larger the engine, the less difference. I'd say about 10% on average.

crosstownk

10% would be a good figure. And well worth it if you do a lot of city driving. I'd a Passat TDI Auto a while back and it was getting me 500+ miles per tank in city drivng with the A/C on.

the_batman

It really depends on the drivers driving style. If I drove around in a manual and spent most of my time red lining in second gear then my fuel economy is going to be worse than an automatic.

I think people can have more control of fuel economy when driving a manual, but their fuel economy can vary up or down more depending on their driving style.

An automatic will have a smaller variance based on the drivers style because the gear changes will be managed by a computer rather than a person.

bazz26

blobert wrote:

Hi there,

I know that you can get better fuel economy out of a manual than an automatic car but does anyone know how much (a rough idea of the percentage)?

Due to my work I've been doing a lot of city centre driving recently and I'm getting very sick of driving a manual all day. I know a lot of taxi drivers drive automatics, otherwise they'd have a sore left leg I'd imagine.

Fuel economy is important to me so like I said I'm just wondering how much worse that is likely to be for the sake of comfort in an automatic.

Any advise would be much appreciated.

Maybe a diesel car with an auto box is what your looking for.

Wishbone Ash

the_batman wrote:

An automatic will have a smaller variance based on the drivers style because the gear changes will be managed by a computer rather than a person.

Yes but if you constantly used the kick down facility the economy would nose dive also. I think the OP is referring to average fuel consumption.

the_batman

I did a check on a few cars, based on the published figures and was was really surprised at the variances across different manufacturers:


Fuel consumption is in miles per gallon and listsed as Urban/Extra Urban/Combined

Saab 95 2.0t
Manual
23.3/42.8/32.8
Auto
19.0/37.2/27.4

That is a difference of between 15 and 22%.

Ford Mondeo 2.0 Duratec HE (145 PS)

Manual
25.2/48.7/36.2

Durashift 4-speed automatic
22.4/39.2/31.0

That is a difference of between 12 and 25%.

BMW 330 SE Coupe
Manual
22.1/43.5/32.1

Auto
21.9/41.5/31.4

That is a difference of between 1 and 5%.


BMW 530i SE Saloon
Manual
22.4/42.8/32.1

Auto
20.8/41.5/30.4

That is a difference of between 3 and 8%.


VW Passat Sport 2.0 FSI 200PS
Manual
25.0/44.1/34.4
22.1/41.5/31.4

That is a difference of between 6 and 13%.

unkel

the_batman wrote:

Ford Mondeo 2.0 Duratec HE (145 PS)

Manual
25.2/48.7/36.2

Durashift 4-speed automatic
22.4/39.2/31.0

That is a difference of between 12 and 25%

It is shameful a brand new Mondeo comes with a 4-speed auto, no wonder fuel consumption is that sh!te

JohnCleary

I did 600 miles with 70euro of diesel in an auto 530 estate. 250 of those miles I was pulling a 1.5tonne twin axle trailer... I was well impressed

AMurphy

I's say it depends on driving style, loading, driving conditions, Air Con or none, design of AT, etc.
I'd expect 5% for exactly the cam car, drive and conditions, the only exception being the AT. However AT oftern comes with Air Con, so in that case I'd increase the difference to 10% for a Std Manual w/o AC to an A/T + A/C.

"Official" MPG figures mean very little to the general driver. Those figures are based on a std test, which may or may not (generally not) represent your driving.
eg, our van (3.3L-V6, 12V) is rated at 24mpg (USG), not a great performer by any gauge. A friends Acura (3.5-V6 - 24V), is rated at 26mpg.
We (my wife) is getting (measured) 51Kmls/2500 Gal =~ 20mpg, while his trip computer has calculated 18mpg Average.
On along trip on open highway I get 24+, maybe even 26.

Nissal Quest 4sp A/T is rated at 24mpg, the same vehicle with a 5sp AT is 23mpg, why with more gears is the mpg lower, I'd expect it to be higher

On a taxi in stop n go traffic, the A/T is definitely a winner. Also definitely a great asset is you have a broken left ankle.

maidhc

JohnCleary wrote:

I did 600 miles with 70euro of diesel in an auto 530 estate. 250 of those miles I was pulling a 1.5tonne twin axle trailer... I was well impressed

Was the trailer loaded?!?

unkel wrote:

It is shameful a brand new Mondeo comes with a 4-speed auto, no wonder fuel consumption is that sh!te

Ford's autos were and still are crap

unkel

maidhc wrote:

Ford's autos were and still are crap

That's a pity. My previous car, which is now nearly 13 years old, had a smooth 5-speed autobox

I have no figures to back it up, but I get the impression that the market share of automatics in Europe is on the increase, especially in the executive segments where most autos are quite refined these days

the_batman

unkel wrote:

I have no figures to back it up, but I get the impression that the market share of automatics in Europe is on the increase, especially in the executive segments where most autos are quite refined these days

I don't think I will ever go back to driving a manual. With all the tipronic and paddle shift options available you get the best of both worlds.

prospect

I am not a Ford fan but WTF are you all on about?

"It is shameful a brand new Mondeo comes with a 4-speed auto, no wonder fuel consumption is that sh!te"
"Ford's autos were and still are crap"

Just looking at the combined MPG for each car listed above, in its AUTO version:

Saab - 27.4mpg
Ford - 31.0mpg
BMW 3- 31.4mpg
BMW 5 - 30.4mpg
VW - 31.4mpg

The way I look at it, the Saab and 5 series are worse for economy, and the VW and 3 series are only BARELY better.

Seth Brundle

what models are you comparing there prospect?

prospect

kbannon wrote:

what models are you comparing there prospect?

The ones listed above in the_batman's post.

Seth Brundle

apologies - I realised that afterwards.
Not entirely fair throwing two 3L cars in there!
The 320d ES gives (Urban/Extra urban/Combined) (mpg)
manual: 36.2 / 62.8 / 49.6
auto: 31 / 53.3 / 42.2
The 520dSE gives
manual:35.3 / 60.1 / 47.9
auto: 30.4 / 51.4 / 40.9

However, the differences are still quite large

prospect

Maybe so, but I think the comments quoted in my earlier posts were a bit harsh. The manual mondeo seems to have good fuel consumption, and the auto seems to be average.

JohnCleary

maidhc wrote:

Was the trailer loaded?!?

Yes I meant that it weighed the 1.5tonne loaded

unkel

prospect wrote:

I am not a Ford fan but WTF are you all on about?

The BMW 330i auto uses up to 5% more fuel than the manual
The Mondeo 2.0 auto uses up to 25% more fuel than the manual

I have no doubt that this huge extra fuel consumption is caused by the lack of more gears

Also the 3.0l 6-cylinder BMW 3-series auto uses about the same fuel overall as the 2.0l 4-cylinder Mondeo auto

prospect

unkel wrote:

The BMW 330i auto uses up to 5% more fuel than the manual
The Mondeo 2.0 auto uses up to 25% more fuel than the manual

I have no doubt that this huge extra fuel consumption is caused by the lack of more gears

Also the 3.0l 6-cylinder BMW 3-series auto uses about the same fuel overall as the 2.0l 4-cylinder Mondeo auto

However the bottom line is that they both have similar consumptions in their auto guises!
I would read it as the others have terrible fuel consumption in the manual versions.

unkel

prospect wrote:

However the bottom line is that they both have similar consumptions in their auto guises!

True. But my second point then is that you're comparing a seriously fast saloon (0-100km/h in 6.6s) with a rather sedate saloon (0-100km/h in 11.4s). One would expect the latter to be much more economical even in the official mix

holly_johnson

I have a 1.8L Volvo S40 automatic which I changed to from a 1.8L VW Passat.

I reckon it's much heavier on petrol than the VW.
I used to get two weeks out of a tank of petrol and now I get approx 10 days.
Enough to notice it in the pocket!

golfnuts

I've a BMW 320i Auto. On a full tank I'd barely get up to 400 miles...work is a 300 mile round trip per week !

prospect

unkel wrote:

But my second point then is that you're comparing a seriously fast saloon (0-100km/h in 6.6s) with a rather sedate saloon (0-100km/h in 11.4s). One would expect the latter to be much more economical even in the official mix

I agree with that.
However, I still think that saying "no wonder fuel consumption is that sh!te" is a bit extreme.

dubstub

AMurphy wrote:

I's say it depends on driving style, loading, driving conditions, Air Con or none, design of AT, etc.

Does Air Conditioning really make that much of a difference? I seem to remember some Top Gear (I think) segment comparing using Air Con to driving with a window down and the extra wind resistance from leaving the window down reduced MPG more than Air Con.

unkel

dubstub wrote:

Does Air Conditioning really make that much of a difference?

Depends on things such as the temp difference between inside and outside the car. A ballpark figure for using aircon is 10% increase in fuel consumption

dubstub wrote:

comparing using Air Con to driving with a window down and the extra wind resistance from leaving the window down reduced MPG more than Air Con.

Depends on other things such as speed of vehicle. At low speeds having a window open doesn't really impact fuel consumption. At 200km/h I guess consumption could increase by who knows, 30-40%

AMurphy

dubstub wrote:

Does Air Conditioning really make that much of a difference? I seem to remember some Top Gear (I think) segment comparing using Air Con to driving with a window down and the extra wind resistance from leaving the window down reduced MPG more than Air Con.

Depends on the size of the compressor and the type of "freon". I had a 1.6L German built Fiesta Ghai with A/C once and when the AC kicked in the car nearly stopped, had to turn it off to pass anything.
I also had a Fiat 1.9L (I think) ROI rental a few years ago with AC and while the car did not baulk with the AC on, it did not cool very well either.
So it depends.... typically your ac drains about 3~5hp and the amount of fuel required to generate that HP. So I'll hazzard a guess, 3 to 10%..

_Kaiser_

My 1.9 TDI (130 Bhp) Auto Passat does around 600 miles to a full tank, but then I do must of my driving on R/N/M-roads at 80-120 kph which helps

(Love my Auto Passat )

AMurphy

Might help if we knew how large/small the tank is.