[tmwanakambwa]

I have noticed high consumption of fuel lately on my subaru legacy even after changing the oil and air filter not the spark plugs. Please advise

[zddiab]

Hi,

I have a BMW 2006 320i 18HP (150). I have a fuel consumption problem, the car is not providing any better then 150Km per 20Liter. It should easily get the 200Km per 20Liter. Any special reason for that. The Car is somehow new, and all services are in green lights, (as OK for service). Why should I have that low cunsumption then!

Thank You.

[ebaines]

FYI - for those of us on this side of the pond 7.5Km/L is equivalent to 17.5 MPG.

zddiab - you have an '06 and yet you say "the car is somehow new?" It's not new - it's 6 years old. If the service lights are all green that means the previous owner had them reset, but it's not a guarantee that all services have been performed. I would suggest having a qualified garage or BMW dealer do an inspection for you - perhaps there's an issue with the fuel or intake system. But the first thing to check are tire inflation pressures.

[zddiab]

FYI - for those of us on this side of the pond 7.5Km/L is equivalent to 17.5 MPG.

zddiab - you have an '06 and yet you say "the car is somehow new?" It's not new - it's 6 years old. If the service lights are all green that means the previous owner had them reset, but it's not a guarantee that all services have been performed. I would suggest having a qualified garage or BMW dealer do an inspection for you - perhaps there's an issue with the fuel or intake system. But the first thing to check are tire inflation pressures.

Hi,

What I meant by New is that the car is still not used a lot, though its 2006. I will check the tires, but also don't your think the spark plugs have a role as well ? Thanks a lot.

[ebaines]

Hi,

what i meant by New is that the car is still not used a lot, though its 2006. I will check the tires, but also dont your think the spark plugs have a role as well ? thanks a lot.

Could be, though modern plugs in fuel injected cars typically don't foul unless there's an issue with the air/fuel mixture - especially if your car is low mileage. Again, have a garage check it out.

[Stratmando]

Air Filter, Tune up, tire pressure, and brakes dragging.

[Stratmando]

Vehicles weight and shape are also factors.

[zddiab]

The fuel used must be unleaded 95 or unleaded 98?

[ebaines]

the fuel used must be unleaded 95 or unleaded 98 ??

Check the owner's manual for recommended fuel octane. I think the basic recommendation is 95. However - octane has little to no effect on fuel mileage.

Note to US & Canada readers - octane as advertised in Europe is under the RON (Reasearch Octabe Number) system. Here in the US and Canada we use a system called Anti-Knock Index (AKI), which is an average of RON and MON (Motor Octane Number), and you see indicated as (RON+MON)/2 on fuell pumps. RON tends to be about 5 points higher than AKI. So their 95 and 98 is about equivalent to our 91 and 93.

[Stratmando]

Check the owner's manual for recommended fuel octane. However - octane has little to no effect on fuel mileage.

Note to US readers - octane as advertised in the UK is under the RON (Reasearch Octabe Number) system. Here in the US we use a sytem called Anti-Knock Index (AKI), which is an average of RON and MON (Motor Octane Number), and you see indicated as (RON+MON)/2 on fuell pumps. RON tends to be about 5 points higher than AKI. So their 95 or 98 is equivalent to our 90 or 93.

I thought The Higher octanes got better Mileage?

[ebaines]

I thought The Higher octanes got better Mileage?

In general - no, as long as you use the minimum recommended by the manufacturer. For BMW in the US it's 91 octane or higher. If you use 93 instead of 91 you will see virtually no benefit in terms of mileage or performance. But if you drop to 87 the engine will compensate by retarding ignition timing - you may sense the engine struggling a bit, especially under heavy load (accelerating up a hill, pulling a trailer, etc) and your mileage may suffer. So use the minimum recommended and that will be optimum.

By the way, in the US one of the factors that can significantly affect gas mileage is the use of ethanol blends. Ethanol has about 33% less energy content per gallon than gasoline, and so when they blend up to 10% ethanol into the gas your mileage will be reduced by about 3%. Cars that use E85 (85% ethanol) can expect about a 30% decrease in MPG. This despite the fact that ethanol actually has a higher octane rating than gasoline!

[Stratmando]

Strange.