How economical is your Golf?

[SammoVWT]

I weigh about 12.5 stone. Perhaps if i could get back to my fighting weight and by that I mean my weight when I was working and hence more active, I could also get better mpg! Imagine the appalling mpg our friends across the pond must get, if we assume that so many of them are obese at least according to what we read and see on our TVs.

Why do you think most of their cars are at least a 3 litre displacement? :P I imagine it would be like towing a caravan

[Keithuk]

Imagine the appalling mpg our friends across the pond must get,

Don't forget our friends across the pond calculate in US mpg which is slightly less than ours. It makes me think when I see 35mpg for 2.0 diesel but its the States.

[rachelisadog]

Miles done = 704.1
Fuel in = 49.28
Torque = 64.95
MFD1 = 58.9
MFD2 = 54.7
Range = 40

Best ever so far and doubt i'll match it!

Miles done = 710.1
Fuel in = 50.22
Torque = 64.28
MFD1 = n/a
MFD2 = 55.3
Range = 30

Not quite as good as last time but still very good if hard work, well, slow work

[BigApple]

GTD DSG 18000miles

Calculated average since new = 46mpg and improving.

Best trip computer run - 52.8mpg.

[HHGTTG]

Came home from a pub visit last night which was a journey of about 11 miles and ended up with this figure. The journey was mainly downhill all the way if you know what I mean as it was from the top of the North Downs.

Sorry about the quality but it was taken with my mobile phone's 2mp camera.

[Bob_S]

The biggest saving on weight is to only half fill the fuel tank, a good compromise between weight and the hassle factor of filling up more often. Diesel weighs about 2lbs/Litre.

The specific gravity of diesel is between 0.81 and 0.96, which means a litre of diesel will weigh between 810 and 960 grammes. Lets take the higher reading and round it off to 1 kilo per litre. A mark 6 Golf has a tank capacity of 55 litres which means a full tank of fuel will weigh 55kg. So by half filling the tank you save 27.5kg in weight. The weight of the car is in the region of 1300kg, so the weight saving equates to 2% of the total weight of the car. How much difference is that really going to make?

You will make more diference by driving more slowly, lifting off early as a result of better forward observation and being more clever with your driving than you ever would by only half filling the tank.

[david25]

If you want to make a real improvement in CRUISING mpg then get this kit fitted for around £150 - £200

http://www.wagenstad.com/index.php?m...&page=8-825-15

Users are claiming improvement of between 0.2 - 0.4 l / 100 km.

Its basically the kit used on VW Golf eco platforms (Bluemotion) and some performance variants (which help their top speed).

Obviously, BM drivers can't really do any more;

Driving with half tank = more stops for fuel
Lots of stop/start driving, well you already have stop/start stuff, you'd need to remove a significant amount of weight to impact that
Lots of cruising, drive slower, car already has optimised aero, perhaps some nice lowering springs from VWR and the like???

EDIT

If you want to see it fitted, check http://www.viper67.de/der-r-in-rising-blue/die-technik/ (bottom of page, you will need Flash)

[Hughesynights]

At a constant speed, weight shouldn't make any difference. As there is no change in velocity, there is no change in the kinetic energy of the car, so you don't need to put any more energy in. Cruising down the motorway at 70 you're overcoming aerodynamic drag, and friction in the drivetrain, with the road and in the wheel bearings. There might, if anything be a tiny, not even noticeable, improvement when cruising fully loaded, as the car sits lower to the ground, which improves aerodynamics.

In general I think you are right, however weight makes a small difference, even at constant speed.

Most of the rolling resistance is caused by hysteresis in the rubber of the tyre generating heat. Friction in the drive train is a much smaller component.
Heavier load on the tyre produces more flex, because the base of the tyre is flattened each time it rolls around.
To a certain extent this can be offset by increasing tyre pressure, effectively keeping the tyre more round. However, there is a limit to how much pressure you can run, the tyre doesn't have the strength and the ride becomes poor. Skipping over the road surface can make mpg worse, as energy is lost in the dampers. Less weight is therefore always better.

Increasing tyre pressure increases mpg because the reduced flex of the rubber reduces hysteresis. This is why hypermilers run the max sidewall pressure.

Low rolling resistance tyres use silica in the compound to reduce hysteresis. Reducing the weight of the car would do the same.

[rachelisadog]

Miles done = 710.1
Fuel in = 50.22
Torque = 64.28
MFD1 = n/a
MFD2 = 55.3
Range = 30

Not quite as good as last time but still very good if hard work, well, slow work

Miles done = 737
Fuel = 50.03
Torque = 66.97
MFD1 = 62.8
MFD2 = 66.8
Range = 40

Now, a couple of things to note here.
About 300 miles prior to this the car was serviced and the software updated as per a lot of folks on here and for me at least it has increased the already quite frugal MPG so that is good news.
Also, for a time, the miles down and range did add up to 800 miles alas, due to some A/C use and a bit of being stuck in traffic this did drop but still very happy with the figures even if, 58mph on the motorway is my self-imposed limit lol

One other thing i noticed. A few days after the 1st anniversary of me owning the car, the MFD2 figure amended itself, didn't reset, amended to a higher figure more in keeping with the figures i have obtained using the torgue mpg calculator
Is this normal after this period of time?

[Keithuk]

You can change/reset the MFD2 value as your driving so it recalculates on current speed and throttle position. I was cruising up the motorway yesterday at around 80mph and the MFD1 was showing 54.9mpg and MFD2 was showing 42.3mpg. After it recalculated MFD2 was showing 79.2mpg for half a mile then slowly dropped down to 58.6mpg and stuck there for the rest of the motorway trip. This morning when I set off the MFD2 showed 53.4mpg.