Can i improve economy of an automatic?

cyclonebri1

Sirbendy wrote: »

indeedy. My old Astra3 1.6 auto would easily crack 400 miles to a tank, more often 450. I drove it with light throttle, if I wanted to overtake etc I'd flick the sports button and let that do a changedown instead of walloping the throttle, it worked beautifully.

People who had Manual Astra3 1.4/1.6s at work were continually whining that they got naff all to a tank (300 miles)..heh.

Now I've got an Astra mk4, 1.6MPi auto...I drive it the same, yet I can barely hit 350 on a tank. Same size tank, same everything bar the MPi (as the Astra3 was SPi), and the fact this Mk4 is drive by wire.

I think on drive by wire autos you're a bit hamstrung..on older cable driven jobbies you could vary the throttle infinitely..on a drive by wire, you only have logical absolutes to work with. That's about the only thing I can see with mine.

I could of course fit the injection manifold from my spare Astra3 MPi into the MK4, but I suspect it'd complain..:rotfl:

Miles per tank equates to sweet !!!! all

You need to elaborate

vikingaero

Easiest way to get better MPG is to push the gear lever from D to N when stationary at lights. Then it's a matter of a quick flick of the lever back into D to get moving.

DaveF327

I drive an auto and I get economy by understanding exactly when gears are prone to change, then using careful accelerator pressure. I can manually select 2 or 1, or force the overdrive off, but other than that, I have to use D. Setting economy mode instead of sport can affect gear change timing and therefore economy. Some automatics have an "Ice and Snow" mode which uses higher gears wherever possible. Try using that if you have one.

Regarding the manual selector on the car you're looking at, then by all means use this to override the gear that the D position chooses for you, providing it always allows that. From experience with cars that have manual selects, once your speed goes below a certain threshold in manual mode, any high gear will automatically shift down to a lower one to prevent engine labouring or stalling, but this gear will not shift up again for you. You need to keep an eye on this and not mentally drift off into old auto mode and wonder why your engine is about to explode on a motorway slip road.

vikingaero wrote: »

Easiest way to get better MPG is to push the gear lever from D to N when stationary at lights. Then it's a matter of a quick flick of the lever back into D to get moving.

Is there a reliable source of that information?

Gloomendoom

DaveF327 wrote: »

From experience with cars that have manual selects, once your speed goes below a certain threshold in manual mode, any high gear will automatically shift down to a lower one to prevent engine labouring or stalling, but this gear will not shift up again for you. You need to keep an eye on this and not mentally drift off into old auto mode and wonder why your engine is about to explode on a motorway slip road.

Most autos will shift up to the next gear when you approach the red line to prevent engine damage... even if you manually lock them into a low gear.

Sirbendy

Good point on the weight diff between G and F..still a PITA though! Astra-G and derivative platform autos (and previous gen Vectra-Bs) with the AF13II and AF17 autoboxes have "neutral shift on stop" built in. I'm still looking for a way to disable it with the laptop. Good idea, but the damn thing occasionally rolls back a fair bit on releasing the brakes.

bigjl

The reasons why an auto is less economical than the equivalent manual is simply down to transmission losses, though I would expect that the new vw DSG box would be the same as a manual since it is a manual with two clutches.

And also the way the box will drop a gear when you accelerate, whereas in manual car the vehicle would stay in the same gear, thus in a dirsel car you can keep the revs low, ride the torque and save some fuel.

I have used the Zafira Auto in manual mode, it is sluggish, never changes when you want it to, when you change down it won't let you if by downchanging the revs would be above a set limit.

There is a Zafira that is available with the old 4 speed autobox, but not sure what it is available in.

There is no way to get good fuel economy from an Auto, and most certainly not from a Zafira diesel auto.

Passat 140hp TDi with DSG box, high 30's, low 40's on a motorway run.

Zafira 120cdti with 6 speed tiptronic box, less than 20 round town, at night whilst on mobile area cover, low 20's.

Vauxhall Omega with 4 speed autobox and the BMW 6 cylinder diesel engine, 25-28 round town, 32 on a run.

All these figures are based on my own experience, over tens of thousands of miles.

Interestingly, Subaru Legacy Saloon 2.0 Petrol, 4 speed tiptronic box, 2004/04, 38mpg on a run, 32-35 round town, LPG conversion anyone?

wazza

Been for a drive in a zafira 120bhp automatic. It was nice but not as responsive as i hoped. Kept an eye on the fuel consumption around town and dual carriageway, it was in the high 20s low 30s.

As it has been said the car is a gear lower than you would have in a manual box while accelerating but when you ease off the accelerator it goes up a gear.

I feel it may be best to assume i would get the same fuel consumption figures as a manual petrol car.

harveybobbles

Isnt it about time the two threads were merged into one...?!

Btw, and auto 5 series is better on fuel than a manual. We often used to be able to make 528i and 530i auto do mid 30's...

Inactive

harveybobbles wrote: »

Isnt it about time the two threads were merged into one...?!

.

Agreed, I keep thinking that my computer is faulty, reading identical posts in 2 threads is a bit silly.

wazza

well initally i was thinking of buying either an automatic or semi-automatic car, had not made my choice. Was toying with pug 3008, zafira auto as well as others.

This post was created because i was wondering if i had a normal automatic and it had a feature where you can change the gears yourself. Will that improve economy if i changed the gears myself?

Someone down the road has a new zafira elite auto with leather seat and all other gizmos. Just loved it. Created the other post to see if someone had any experience with the zafira auto.