3.8 V6 Fuel Economy Improvements Bang for Buck

[turbo_vp_v6]

In my vz I put a twin 2 1/2 inch in with bigger cats and pacemaker and I went down to 7.8 l/100

 

[Cheap6]

In terms of $ saving per $ spent LPG will be the best value; fuel costs will probably be close to half, depending on local fuel costs. With the rebate, break even time will typically be around 6 months.

The O2 sensors are cheap enough if the current ones are not working properly.

'Plugs and leads likewise.

Apart from tyre pressures, oil etc. ^^...^ wheel alignment maybe?

You can pull back some of the penalty of using the A/C by only switching it on when decelerating - kinetic energy recovery. If you want to spend a few dollars (<$30) you can route the A/C switch wiring through a switch on the brake pedal to automate the process. You need a timer circuit to hold the A/C on and prevent cycling the A/C clutch rapidly with a very brief brake application. About 10 secs works for me. I have an RC timer connected to a transistor in series with the A/C and brake switches. You need an overide/bypass switch for highway driving where there is little brake application.

Type "ecomodder" into a search engine for more tips.

 

[peterlonz]

Good God some complaints .................
I have just completed my economy check (VX, V6, 136,600Km).
The result was 16.2 L/100 Km -------------- frighteningly expensive at about $27/100Km.
I made a mistake you think?
Well I was careful & I have checked my figures.
Urban running around doing mainly shopping duties.
Typical trip distance about 10 to 15 minutes, 30 min run about once per fortnight.
Driving style: "Old woman" very easy on take off, & never exceed speed limit (for reasons of economy only).
Vehicle drives nicely, idles well, starts readily, has "sports exhaust" fitted by previous owner (details not known), throttle body & MAS recently cleaned.
I was advised to run a tank of 98 octane so the above is from 98!
What the heck could be so wrong & what can I do next.
Has anyone seen economy as bad as this?

 

[EYY]

For stop start driving that's about right. At 100-110 mine gets around 7-8L per 100km. On average with a mix of driving it gets around 10-11. With mostly city, stop start driving, it's closer to 15.

It will use more fuel when cold too, so short trips aren't the best for economy.

 

[Hertz Donut]

I normally get around 12-12.5l/100km, mainly short trips. Open road I've seen as low as 7/91l/100km. 288,000km on a badly-maintained old VS, O2 sensors haven't been touched in the time I've owned it (15 years). It improved markedly after I did the LIM gaskets, I was getting figures similar to yours (peterlonz) beforehand. I think half the time it's pot luck with these engines.

 

[Immortality]

Diff gears work wonders for V6 engines and fuel economy especially if you do a lot of stop/start driving.

 

[Immortality]

Good God some complaints .................
I have just completed my economy check (VX, V6, 136,600Km).
The result was 16.2 L/100 Km -------------- frighteningly expensive at about $27/100Km.
I made a mistake you think?
Well I was careful & I have checked my figures.
Urban running around doing mainly shopping duties.
Typical trip distance about 10 to 15 minutes, 30 min run about once per fortnight.
Driving style: "Old woman" very easy on take off, & never exceed speed limit (for reasons of economy only).
Vehicle drives nicely, idles well, starts readily, has "sports exhaust" fitted by previous owner (details not known), throttle body & MAS recently cleaned.
I was advised to run a tank of 98 octane so the above is from 98!
What the heck could be so wrong & what can I do next.
Has anyone seen economy as bad as this?

What is your average speed on the trip computer?

Personally, I don't think you'll get better economy running 98 fuel in a car that is tuned for 91. 98 ron fuel already has some of the additives used in fuel system cleaners so it's good for that reason but IMHO that is about it.

 

[Wats_in_a_name]

I had the same issue as the OP in my 2002 VY. I was getting about 13.5l per 100k. I managed to fix this using several ways. Firstly I started using less revs when taking off. I used to use about 3,500 revs when getting off the line at lights but I changed this to about 2,500. 2,500 revs in a Commodore I find will get you off the line as quick as if not quicker than most cars (although of course you won't beat the super fast people).

Also, another poster said to use NGK spark plugs for a VY instead of Bosch which I found as well. My mechanic also tuned my car and I found a big improvement in fuel economy and when putting the power down. Also, I swapped the tyres. I had Bridgestones at the time but now with my VZ I have gone for Michelins. So if you can afford it (they are a bit more expensive) I would go for tyres like that.

My fuel economy improved to about 11 litres per 100km in some cases going as low as 9.3 litres per 100ks in the city(although most of this was done on 70km/h roads going against the traffic). I also got more than 1,000kms from a tank, and once when I reset the trip meter the range went up to 1,200kms. On highway driving the fuel economy was generally in the 8s although it did get down to the 7s from time to time.

 

[Hertz Donut]

I used to use about 3,500 revs when getting off the line at lights but I changed this to about 2,500. 2,500 revs in a Commodore I find will get you off the line as quick as if not quicker than most cars (although of course you won't beat the super fast people).

Wait, what? By "lights" are you referring to the tree at the drag strip? On the street you should barely need much more than idle rpm to get a Commodore moving.

[edit] Unless you're running a big cam of course... [/edit]

 

[Husky]

Wait, what? By "lights" are you referring to the tree at the drag strip? On the street you should barely need much more than idle rpm to get a Commodore moving.

[edit] Unless you're running a big cam of course... [/edit]

I'm assuming he means revving to 3500 before letting it change gears.