Astra 2.0 DTi - Fuel consumption

[hougtimo]

Hi Guys - You might wanna grab a cuppa before reading this - could be rather long!

So, I have a 2001 (Y-Reg | 88,000m) Astra 2.0 DTi which I've had for just over a month now. It is my first diesel since passing my test last year (which was in a 307 HDI 1.6), so I've kinda got used to driving petrols.

When I first got the Astra I drove it pretty much like my petrols - well that didn't work too well at all. It averaged under 40mpg & didn't have the get-up-and-go I thought it would!

So I've gradually changed my driving style and it now seems to return a much better figure (Around 50 mpg - combined) which I was thinking is pretty good tbh! I've also found that when accelerating it is better to hold it in a lower gear for a bit longer, rather than changing up & putting your foot down more. Usually change up at around 2500rpm when accelerating briskly.

Anyways, I was happy with this untill I was stranded in Sheffield on thursday night with less than £5 on me. My fuel light was flashing (less than 2 litres left in the tank) and had to get back to Hull. So I put the £5 of diesel in (111.9 ppl) and on the way home managed too eeek out 68 miles before the fuel light came on again. I drove bang on 60 mph - most of it is motorway - M18, then M62. This has kinda given me the urge to see if i can do better yet!!!

I've done all the usual bits - it's just been serviced, no roof rack/rails, no rubbish in the boot, tyre pressures set to the "fully loaded" figures etc.... So really I'm just looking for tips on my driving.

I read somewhere that engines run at their maximum efficiency at 1/3 of the total rev range - which is 2000rpm in the astra - in 5th gear that is dead on 60mph. Would it benefit me to drive at the "mythical" 56mph? What rpm should I be changing gear at? As I say usually I change up between 2000 - 2500 rpm. I find that changing at 2000rpm usually kills my acceleration, unless i plonk my foot down - which obviously isn't good!

I guess keeping it in the torque range is the best option?

Any advice would be great!

Cheers

 

[obi_waynne]

A good read. I see you've discovered the benefits of eco driving!

Peak torque range does tend to give the best economy. Changing up too quickly is as bad as not changing up quickly enough.

Aim to use the brakes as little as possible. Get up to speed without dawdling, but you don't want to rev the engine hard.

You need to remember that the amount of fuel going into the engine is directly proportional to the amount of throttle you are using. 2/3 throttle still gives around 80% of your engines power so this should be more than adequate.

Next up when you replace the tyres get some with low rolling resistance like the Michelin Energy.

Ensure you wheel bearings are in good order, friction will cause power/economy losses.

 

[hougtimo]

Cheers for the reply - Clarified a couple of points for me *thumbsup*

Had a bit of a roadtrip to do yesterday, fuel light was flashing when i filled up - put £20 of diesel in & now on 210 miles and the light hasn't even come on yet! Kinda looking towards 60ish mpg! (If i can get another 30 miles out, which i reckon i can )

Stuck to 65mph mostly motorway and no harsh accelerating or braking.

I do seem to have developed a squeal from one of the wheels when I've been on the go for a bit - think it's brake related as braking stops it. Will have to get that looked at as obviously it won't be helping the economy situation!

 

[thexav]

If you have a family you could always get them to push it in slow traffic

Hello by the way and welcome to the mad house.

 

[obi_waynne]

A dragging break will not be helping

 

[pgarner]

sounds a bit strange but go for a remap for more power and torque,

just about all diesel owners see an increase in economy when driving normally

 

[obi_waynne]

Good point PG. But that is providing you don't drive it harder to take advantage of the power.

 

[HDi fun]

"sounds a bit strange but go for a remap for more power and torque,

just about all diesel owners see an increase in economy when driving normally"

I can vouch for that but my 'normal' driving style is still pretty bloody purposeful. I suppose if I used every last ounce all the time then I'd see an increase in consumption.

But I don't need every last ounce - it goes very nicely if you change up by 2500rpm.

Change up at 3000-3250 and you're supplied with instant and effortless go.

Leave it 'til over 4000 and you're going too fast, too soon.