BMW 330ci fuel economy - how is it possible?
Discussion
CampDad's spanking new Efficent Dynamics 320D has averaged 57mpg. Lots of motorway, some town, never nailed it too much but not a slow driving either (80mph on motorway)
It also revs well, produces about 127g of CO2/Km and is refined from about 5mph, though at idle it is still lumpy like all dervs.
It's 50BHP and 10mph up on his old X-type Jag. In short, it's pretty amazing. why anyone would buy a non-derv 3 series new is beyond me
It also revs well, produces about 127g of CO2/Km and is refined from about 5mph, though at idle it is still lumpy like all dervs.
It's 50BHP and 10mph up on his old X-type Jag. In short, it's pretty amazing. why anyone would buy a non-derv 3 series new is beyond me
WildCards said:
RobM77 said:
272bhp (equal to a 1980s Ferrari 328)
50.4mpg extra urban and 173g/km of CO2 (equal to a year 2000 model 1.0 litre Micra)
Any engine people out there? How is this possible?! What has changed so much about engines over the years?
It isn't and it doesn't. Where BMW get their figures from amazes me, my stepdad has had a new 330Ci for a year now and when driving as carefully as possible he can't get anywhere near any of the official figures claimed by BMW. His road tax is £15 cheaper than my 8 year old diesel though, so it's not all bad.50.4mpg extra urban and 173g/km of CO2 (equal to a year 2000 model 1.0 litre Micra)
Any engine people out there? How is this possible?! What has changed so much about engines over the years?
CampDavid said:
CampDad's spanking new Efficent Dynamics 320D has averaged 57mpg. Lots of motorway, some town, never nailed it too much but not a slow driving either (80mph on motorway)
It also revs well, produces about 127g of CO2/Km and is refined from about 5mph, though at idle it is still lumpy like all dervs.
It's 50BHP and 10mph up on his old X-type Jag. In short, it's pretty amazing. why anyone would buy a non-derv 3 series new is beyond me
You seen the MPG for the 320i/318i? given the price difference between petrol & diesel these is now nothing in it/in the petrols favour. However its a different driving style low end thumping torque vs hanging the the engine out to dry on high revs - very nice in a I6.It also revs well, produces about 127g of CO2/Km and is refined from about 5mph, though at idle it is still lumpy like all dervs.
It's 50BHP and 10mph up on his old X-type Jag. In short, it's pretty amazing. why anyone would buy a non-derv 3 series new is beyond me
Yes they have.
Remember the main difference between the old 3ltr BMW petrol vs this one is direct injection & then you have the ED.
A few owners on BMWland etc are getting exceptional MPG out of these new 330i's also the same with the new 330d's 49.6mpg combined...
Talk about competitive advantage.... Merc/VAG/GM what are you doing, still trying to catch up with BMW's last gen units lol.
Remember the main difference between the old 3ltr BMW petrol vs this one is direct injection & then you have the ED.
A few owners on BMWland etc are getting exceptional MPG out of these new 330i's also the same with the new 330d's 49.6mpg combined...
Talk about competitive advantage.... Merc/VAG/GM what are you doing, still trying to catch up with BMW's last gen units lol.
kambites said:
I fail to see how the hell they can hope to get meaningful figures out of that though.
The dynamometer is loaded using figures obtained by coasting the vehicle down to a stand still in Neutral. I.e. The deceleration of the vehicle is measured, and this is used to create a function of load against speed that is applied to the vehicle on the dynamometerOJ said:
kambites said:
I fail to see how the hell they can hope to get meaningful figures out of that though.
The dynamometer is loaded using figures obtained by coasting the vehicle down to a stand still in Neutral. I.e. The deceleration of the vehicle is measured, and this is used to create a function of load against speed that is applied to the vehicle on the dynamometerETA: I'm not questioning whether you're right. I just think it's a stupid way to do it.
Edited by kambites on Thursday 13th November 17:05
kambites said:
OJ said:
kambites said:
I fail to see how the hell they can hope to get meaningful figures out of that though.
The dynamometer is loaded using figures obtained by coasting the vehicle down to a stand still in Neutral. I.e. The deceleration of the vehicle is measured, and this is used to create a function of load against speed that is applied to the vehicle on the dynamometerETA: I'm not questioning whether you're right. I just think it's a stupid way to do it.
Edited by kambites on Thursday 13th November 17:05
Laboratory conditions that all manufacturers adhere to is the only way for these figures to have any meaning from a buyer point of view, so long as buyers are aware that these figures are generated in a lab, which appears not to be the case.
How else is a buyer supposed to compare two differnet manufacturers car for fuel consumption when during testing they were driven in different temperatures on different roads with differing cross winds,etc,etc.
captainzep said:
Pah. Beemer fuel efficiency.
I drove from Kent to Wales the other day and got 36mpg from the old Saab 9-5 Aero 2.3 250bhp turbo engine.
Got bored around Bristol though.
Some 'spirited' driving saw this average dip to about 31mpg...
But still.
That's because it's a turbo, you were off boost on the motorway. What BMW are doing is achieving the mpg with a normally aspirated engine, which is a whole different ballgame.I drove from Kent to Wales the other day and got 36mpg from the old Saab 9-5 Aero 2.3 250bhp turbo engine.
Got bored around Bristol though.
Some 'spirited' driving saw this average dip to about 31mpg...
But still.
kambites said:
It's hard to separate the effect of weight and of aerodynamics on the basis of deceleration alone. A less aerodynamic car will decelerate faster but then so will a lighter one with the same aero. There must be more to it than that?
ETA: I'm not questioning whether you're right. I just think it's a stupid way to do it.
It is on a dyno -- aerodynamics doesn't come into it as the car is stationary!ETA: I'm not questioning whether you're right. I just think it's a stupid way to do it.
I'm surprised they produce mpg figures in the absence of any aero drag. No wonder the extra urban figures are ridiculously high.
Welshbeef said:
You seen the MPG for the 320i/318i? given the price difference between petrol & diesel these is now nothing in it/in the petrols favour. However its a different driving style low end thumping torque vs hanging the the engine out to dry on high revs - very nice in a I6.
This is true, except the 320i and 318i are I4.E30M3SE said:
madou said:
Welshbeef said:
Thats because this new 330i 272bhp 39.x mpg combined engine only came out in Sept08.
Are you off form today, or is Parker's wrong ?Unfortunately Parker's do not provide the combined mpg to one decimal place one the prior version as per the BMW official information on the current version
RobM77 said:
272bhp (equal to a 1980s Ferrari 328)
50.4mpg extra urban and 173g/km of CO2 (equal to a year 2000 model 1.0 litre Micra)
Any engine people out there? How is this possible?! What has changed so much about engines over the years?
50.4mpg extra urban and 173g/km of CO2 (equal to a year 2000 model 1.0 litre Micra)
Any engine people out there? How is this possible?! What has changed so much about engines over the years?
Easy! Pay huge amounts of money upfront for one hugely complex engine with almost every bought-in feature under the sun and then pay huge amounts in servicing and probably never get the potential fuel economy savings back.
These fuel economy & CO2 figures are gathered from the standardised New European Drive Cycle (NEDC) test and bear almost no relation to driving in the real world, and some manufacturers have the opportunity to work these figures better than others.
The test is very benign in terms of engine speeds and loads and therefore with a number of add-on engine & ancillary features it is possible to switch off things that are "not needed". You don't need steering on the test so switch the steering pump off, you don't need much oil flow so set the oil pump to the minimum, you don't need much coolant flow so switch the water pump off, no need to charge the battery...... and so on. Another thing that BMW have done is they've put centrally mounted Gasoline Direct Injection (£££££) de-NOx cats (£££££) and to control the NOx cat regeneration cycle they fit NOx sensors (££££££). The advantage of running centrally mounted direct injection is the ability to run the engine more consistently at lean Air-to-Fuel ratios (AFR), which is great for fuel economy however this produces lots of NOx but very little CO and unburnt hydrocarbons. This means that the pollutants cannot reduce and oxidise each other in a normal three-way cat, and so the NOx has to be captured in a NOx cat. However, as with most things in engineering there is no such thing as a free lunch, the NOx cat will need to be regenerated every so often and to do this the engine will run rich, which is bad for fuel economy, to reduce the captured NOx.
Now some of these systems have debatable benefits over the more realistic engine operation cycle (vane type variable flow oil pumps tend to have quite high friction at higher speeds). The de-NOx strategy is very debatable considering the regeneration cycle (nice tool for the calibrators to use for the NEDC though) and many other manufacturers are going for Stoichiometric AFR over as much as the speed/load range that only requires a conventional 3-way cat (much cheaper and less risky in terms of warranty but will not achieve the same in the NEDC).
BMW are not doing anything that other manufacturers haven't got the engineering capability to do (yes even lowly Weatherspoon's burger/Vernon Kaye/Weak-Tasteless-Lager Ford), however BMW have got the opportunity to pass the cost onto the customer and critically the economies of scale to put this stuff into their engines. Other OEMs have to do more with less, which is sometimes harder than just chucking money at a requirement and this can involve some rather clever engineering (sometimes more expensive upfront engineering but less product cost).
As for the power rating, that it is achieved through adapting the engine to run at higher speeds and higher torque at that speed (and all the compromises & detriments to other engine speeds and loads that go with it). In the case of the BMW 3.0 litre NA it has very expensive machined inlet ports, expensive & bulky tuned length exhaust manifold and because of the direct injection & the twin VVT then the engine can run a higher torque at that engine speed charge cooling from the evaporation of the fuel to run a higher compression ratio and the VVT allows maximum entrapment of air in the cylinder. Again something that other OEMs have the ability to do, but have other factors to consider.
I actually quite admire BMW for what they do because they consistently hit the spot with their market. Also because their engines are smooth, powerful and they sound great. And as for massaging the figures, they are only getting around some rather ill-thought out legislation. However please can we not we not have this bullst that surrounds BMW about their superior engineering, because it is never that simple!
Edited by wheeljack on Thursday 13th November 18:21
wheeljack said:
BMW are not doing anything that other manufacturers haven't got the engineering capability to do (yes even lowly Weatherspoon's burger/Vernon Kaye/Weak-Tasteless-Lager Ford), however BMW have got the opportunity to pass the cost onto the customer and critically the economies of scale to put this stuff into their engines.
Surely that's equivalent to a Wetherspoon’s spokesman saying “yeah there’s nothing Heston Blumenthal can do that we can’t but he’s lucky that he’s got a load of rich clients willing to pay for it”. That isn’t in itself a reason to object to praise being heaped on the Fat Duck.
wheeljack said:
Other OEMs have to do more with less, which is sometimes harder than just chucking money at a requirement and this can involve some rather clever engineering (sometimes more expensive upfront engineering but less product cost).
I suppose that's the equivalent of investing upfront on building an extra section of kitchen for automated potato slicing and chip frying in order to reduce the unit cost of meals.But you're right they are simply playing to different sections of the market.
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