walkermg

Hi

I am a recent convert to the BMW 6 series and have purchased a 3 year old 630i convertible; however the fuel economy seems way off what I expected I am currently reading 20.4 to the gallon (UK), this is under fairly conservative driving aswell. Does this sound right ? can you shed some light on what MPG you get to the gallon out of your 630's please.

Many Thanks

Mark

seoulman

Your mileage will vary depending on many things. How you drive the car, traffic conditions, road conditions, weather, temperature, tires, whether you have the A/C on or not, whether your convertible top is up or down, condition of your engine, among other things.

I think BMW rates your combined average consumption at 28.5 mpg. Manufacturer consumption estimates tend to be optimistic.

To get more accurate information from the members of the forum, you would probably have to provide more details like:

- Where you do most of your driving. In town or on the expressways?
- When you do most of your driving. In heavy, moderate, or light traffic?
- Your driving habits. You would probably need to define 'conservative driving' because driving habits are subjective.

walkermg

Thanks for the reply here is the information to help paint a more accurate picture:

Most of my driving is a 60/40 mix between town and express way (motorway), conservative driving is driving in such a manner as to increase efficiency to see if I could actually increase the MPG so no hard acceleration, this is england so the roof has hardly been down due to rain, air con has been used but not in ernest.
Most of my driving is in fairly light traffic, commute to work is always before the peak rush hour.

I also took a 180 mile motorway journey after resetting the computer and drove at approx 70 and the MPG still only came in at 21MPG.

Let me know if I can provide any other information to help figure this one out.

I appreciate the manufacturers figures are under certain optimum conditions but my audi TT was give or take 5% off of the figures.

Thanks for your help

M

seoulman

Other than driving technique/habits, I'm not sure what else to tell you. Your car isn't that old. What is the mileage you have on it? Do you have service records/history of the car prior to your ownership?

Like I said in my earlier post, it could be alot of things that are causing what the gap in consumption between the manufacturer rating and your real world consumption.

Third party fuel economy ratings for a 2005 330i is 27mpg highway, 18 mpg city, and 21 mpg combined. The engine in this car is the same as the engine in yours. I rechecked the combined fuel economy rating for your car new and it isn't 28.5 mpg. That is the highway mpg (my bad! ). Given this, your fuel consumption isn't that bad. In fact, it is quite average.

I hope this helps.

cobradav

Are you relying on the calculated value or doing your own calculations? My iDrive calculated value is 17 percent off in a negative direction. I calculate each and every tank including average speed and iDrive computed value. I do actual miles driven divided by gallons pumped. Since I do the filling I fill in the same manner each time. In any case my 645Ci (obviously a V8) has a 21.52 miles per gallon (US gallon in this case) average over 68111 miles. Highs of 25+ lows of 12 when driving VERY aggressively about twice a year on long twisty roads. Mine is a daily driver and normal driving is 80/20 (hiway/city) and I fill up on average between 370 and 395 miles per tank. I will travel up to 75 mph for about 10 of the 25 miles one way and then the rest pretty close to 55-60. The winter mileage (w/o AC) tends to be 22+, while the long hot summers here in Florida tend to bring closer to 19-20 mpg. Tires at high end of recommended pressure (35-37 fronts, 38-40 rear).

Car was delivered with iDrive computing about 5% high. I tried to adjust it to dead on and screwed it up where it is now. I just have not tried to bring it in closer as I prefer the pessimistic view.

seoulman

320d touring

2 things you can do to improve fuel economy:

1 change the air filter
2 get new software

First option worked fine for my E61 and the second made the consumption drop from 9L/100km to 7,5L/100km in my Cooper S.

walkermg

Thanks again for the replies, I will do some of my own calculations and compare them to the Idrive.

Thanks again