[V6-12v] fuel efficiency

[James Whitehouse]

Guys,

Those of us in Europe where petrol (gas) is horribly expensive have, as Tom pointed out, been aware of the effects of car setup and driving style for years. I remember doing the 'coasting downhill' technique Tom describes when I owned my first Audi (generation 1 80 1.8 - great car, never let me down) because I was a student with little money. I was living in France as a student near Nice and on the autoroutes around there you have big hill climbs but then massive descents. Sometimes I could coast as fast downhill there as other people on power. Nowadays I drive reasonably sensibly, keep the engine in good condition and just suck up the cost of fuel. Tyre pressures make a huge difference also - I usually inflate all tyres to the high-load/high-speed setting (actually I use 36 psi all around unless I have a heavy load in the rear). This often improves handling and response in the wet anyway. Also remove any unneccessary weight from the car (in the boot
 (trunk), etc.).

That said, the fuel economy of the 2.8 V6 at least is a heck of a lot higher than 10 mpg! It should be up to 35 mpg for an engine in good condition on a long run (motorway/highway) and in the high 20s for town/urban driving. If it's down in the 10s I'd say you have either a very very heavy right foot, or some kind of problem with the engine mechanically, or with engine management, or you're using the wrong grade of fuel (Super unleaded costs more, but gives better power/economy). Definitely give the engine a good service and health check, definitely check lambda (O2) probes - when they go bad they can read too lean and cause the engine to over enrich, wasting fuel and coking up the engine.

Regards,
James 

--- On Wed, 20/5/09, Tom Christiansen <tomchr at gmail.com> wrote:

From: Tom Christiansen <tomchr at gmail.com>
Subject: Re: [V6-12v] fuel efficiency
To: "Jonathan" <jhhummel at bigpond.com>
Cc: v6-12v at audifans.com
Date: Wednesday, 20 May, 2009, 2:00 PM

Jonathan,

There are a lot of factors that affect fuel economy. How much you are
hauling, tire pressure, etc. But foremost probably your driving habits and
type of driving.

On my 1994 90S that I parted with last year I had about 170000 miles (272000
km) on it. I consistently got 25-26 MPG (10.9 km/l or 9.2 l/100km). Last
summer, when gas was less cheap, I changed my driving habits. Rather than
driving 70 MPH on the highway, I stuck to the posted speed limit of 60 MPH.
That gave another 10-15 % fuel savings. Inspired by some fuel economy
contest in Europe, I also started coasting downhill. Just step on the clutch
and coast - if you need power to steer around something all you have to do
is pop the clutch and it's here... That gave 0-10 % improvement. But
frankly, it was a bit of a pain and the results were very inconsistent. It
did lead to a change in my driving style, though. On the routes I take
regularly, I now coast down even seemingly negligible slopes while
maintaining a constant speed (gravity at work). And I stick to the posted
speed limit. I avoid rapid starts. For the most part anyway... Every once in
a while you gotta have some fun and floor it... :-)

My driving is about 60/40 between highway/city driving. Before I parted with
the 90S, I seem to recall getting 27-28 MPG.

So in short; I don't think fuel economy is a good gauge for how the engine
is fairing. I'd keep an eye of it and analyze changes. But oil consumption
has for me been a better indicator.

~ Tom


On Wed, May 20, 2009 at 2:20 AM, Jonathan <jhhummel at bigpond.com> wrote:

> Hey All,
>
> Just worked out my fuel efficiency last fill up - just cause really.
> Anyway, it
> works out to be about 11.6L/100Km. It's official ecconomy is about 10
> something
> isn't it?
> Anyway, to my point. Is fuel economy a reasonable measure of how your
> engine
> is fairing? As in, that's not bad for a 13yr old engine that has done
> 265000Km.
>
> Car:
> 9 6A4
> 2.6 V6
> 5spd Auto, front wheel drive.
>
> Cheers
>
> Jon
> _______________________________________________
> V6-12v mailing list
> V6-12v at audifans.com
> http://www.audifans.com/mailman/listinfo/v6-12v
>
_______________________________________________
V6-12v mailing list
V6-12v at audifans.com
http://www.audifans.com/mailman/listinfo/v6-12v