Disappointing fuel ecomony

shayser

I don't know what mpg my car does. I do know how many Km I get to a tank, though.

Few weeks ago I traded up a 05 manual for the same model again, this time automatic. The auto is supposed to have slightly better fuel economy than the manual.

On the 05 I was getting between 500km and 550km per tank. On the new car I'm getting just over 400km. Same driving, same routes, same car except now auto and 2 years newer.

Thought it might be the air con as the 05 didn't have one and I had it on nearly all the time in the new car for the first week. But on the second week I didn't put it on at all and noticed hardly any difference.

Woud this be a fault with the car somewhere?

It's a Golf GTI.

ctc_celtic

i always though autos were only more economical on long motorway drives, but less on short and normal driving?
what type of driving do you do?

shayser

Almost all about town. But would this mean 20% less economy than a manual over the same route?

ctc_celtic

the stated difference for a gti is only 7-9% less for urban driving (2006 models)

did they change from a 1.8ltr to a 2.0ltr?

bbability

It may take you a while to adjust to the automatic set up. The tendancy is to put the foot to the floor to get the car up to speed. I know a guy with the same complaint except he was driving a Merc C class 2.2 diesel. He bought an the same car with an auto box this year. I was in the car with him recently and all his talk about poor economy was down to the fact that he buried the pedal to the floor rather than drive it normally.

JoeA3

The aircon makes almost negligible difference. I don't get much more than 450-475kms from a tank in my GTI (manual), maybe a little over 500km on a longer spin. I've my aircon on all the time also.
Give it a little time, it should improve a bit as the engine settles.

colm_mcm

Automatics are harder on fuel. it would be very unusual for an auto to use less fuel than a manual.

stratos

This might help and is advocated by some UK based save petrol/earth group. When moving off in an automatic when the desired speed has been attained feather the accelerator slightly, back of a fraction, your speed will stay the same but you will use less petrol. I sometimes drive an automatic I tend to gun it up to speed but backing off when I hit my desired speed. I dunno if it would save 20% though. Auto gearboxes are heavier than manual ones and don't have direct drive in all gears so mpg is bound to be a bit worse anyway.

colm_mcm

the backing off the throttle would encourage the gearbox to change up a gear.

shayser

Volkwagen state that the auto gives slightly better fuel economy than the manual. I noticed that it changed up much sooner that I did in the manual. I thought good, this might save me a few litres. So, I was surprised to get over 100km less per tank.

stratos

Maybe auto box technology has moved on but i have no idea how an auto box could be more economical than a manual. Auto boxes ar heavy as they have extra clutches they have a fluid coupling on most gears not very efficient. and as you have no engine braking, brake wear is heavier and so running costs more expensive.

R.O.R

If it's a Golf Gti then it's the DSG box rather than an auto. According to VW's UK website the combined fuel consumption on the DSG is slightly better than the manual (35.8mpg against 35.3mpg) but I'd guess that's using the lever or paddles to change rather than letting the box do it automatically.

Try using the DSG shifter to change when you would driving the manual and see if that improves economy rather than using the full auto mode.

barryfitz

Yep I was always of the opinion that autos werent as economical on the fuel. You didnt state whether the new car is brand new or not. If its a brand new car then that might explain the loss in economy, new cars tend to be a bit stiffer (all the parts) and need to be broken in. the mpg should go up after a while if this is the case.

shayser

I'll use the manual shift as much as I can over the next week, hopefully I'll see a difference - to determine there's no fault.

Thie car is brand new. Maybe that's it, as you say. That's good news that the mpg should go up.

galwaytt

is it auto or DSG - I did 9k in a DSG Golf and I can testify it used less fuel than the manual over that distance.

GB15

My last car was an auto and everytime I was stopped I used to put it into neutral. Otherwise the engine is still pushing against the wheels as can be felt as you leave your foot off the brake. I never tested against not putting it into neutral so I don't know how much savings it could make.

It was an old car though so I'm not sure if more advanced autos have technology to reduce fuel consumption when stopped with the gear in drive.

TomMc

As above - try changing gears yourself. In all cars but especially in autos, DSG ... smooth driving is the key. If you stick it in fully auto mode and then press on a bit (over 3,000rpm fairly often), you will see a much bigger appetite for fuel, compared to the manual equivalent. Best way to drive is at a nice steady speed where you do not have to brake anymore than is necessary, so less slowing down & speeding up concerned.

---

Not for the public roads in case the PC brigade are knocking around:
but
Like with racing drivers .... drive into a corner a little bit slower, so you can accelerate that little bit earlier and so exit faster, rather than go in too quickly:eek: , have to brake much harder :eek: and then accelerate again from a relative standstill.

A car is like a woman - needs to be treated right, to get the best out of them.;) Thankfully motors don't have headaches, although some of them pass them on to their owners from time to time.:rolleyes:

shayser

galwaytt wrote:

is it auto or DSG - I did 9k in a DSG Golf and I can testify it used less fuel than the manual over that distance.

It's the DSG. I'm definitely getting a lot less mpg than the manual.





Next time I fill up I'll drive fully manual until the next fill and see what that tells me.

whippet

shayser .. I have about 4500km on my DSG motor now and the ecomomy is much better than it was for the first 2000k. I am getting about 420km from the tank on my run .. where before it was in and around 350km ... mostly very heavy traffic driving (m50 at peak) and when not in traffic with a heafty enough right foot !!