Fuel consumption. Another observation vs E53
 

We now have 1100 miles on our 30d m sport and to be honest I feel slightly mislead by BMW. The suggestion is that the new gen X5s are a)cleaner (cant dispute that as I have no way of measuring) b) more effecient, I do dispute this, I tried to drive our car as gently as I could and at 55mph I did see 34mpg on a flat peice of road, as soon as there was mild throttle input this dipped to 29 mpg, then around town this soon dipped to 23mpg. At motorway speeds I see 29mpg. My old e53 managed 34mpg at motorway speeds and at 55 mph and 26 mpg round town. Speed wise there is very little difference so BMW can you please tell me how the E70 is more effecient for me?. No matter which way you cut it my old one was more economical.
One other suprise is that I can actually get 23 mpg out of my Gen 2 C4s around town, so BMW well done you have created a mid range SUV that is actually less effecient, to me, than a mid range sports car. Congratualtions!!!

Manufacturers are getting better at 'cheating' the official EEC fuel consumption tests. BMW may be bad but it's not alone. Chief offender: Toyota/Lexus with its petrol-electric hybrids

Compare apples to apples: the e53 weights how much and puts out how much HP/Torque and has what interior volume? A heavier, larger vehicle that accelerated faster e70 but uses the less fuel relative to a smaller, "slower" vehicle e53 may be BMW's angle here.


BMW may simply look at how much fuel into the engine puts out how much energy and that the e70 is simply more efficent.

This may be the dynamics part of their efficent dynamics baloney.

Remember that the EEC fuel consumption test that's used in Europe and in much of the world, and is similar to the EPA test used in the USA, is a simulated test. The vehicle in question isn't driven on the road but is put through simulated driving cycles on a rolling-road dyno. The driving cycles simulate 'urban' and 'extra-urban' driving via a series of accelerations, decelerations, constant speed running, idle periods etc. The test wasn't devised by BMW, or any manufacturer for that matter, it's the work of government bureaucrats designed to 'help' the consumer. So when BMW says it cars get Xmpg or use X litres/100km, this is simply the figure it achieves in the relevant EEC or EPA test. BMW, like all manufacturers, goes out of its way to say that real-world fuel consumption will vary from these figures.

True, but once the manufacturers know the cycle, they do tend to tweak the powertrain programming a bit to get good results on the specific cycle.

One year in the past, BMW motorcycles had a bit of a flat spot at a certain RPM, as knowing the placement of the microphone in the European driveby noise test, they tailored the engine controls a bit so that it was not quite as loud as it passed the microphone. Obviously there is a limit to what the manufacturers will do, as if they tweak it so much that driveability and performance are too adversely affected it will cause customer dissatisfaction, but if CAFE fines are at risk, or they find they have made a mistake and need a quick fix, as in the noise problem on the BMW motorcycle, they might tweak it a bit much. It is pure speculation, but I have heard some people question whether some of the transmission lag or jerkiness might be related to such "test cycle tailoring."

That's exactly what I said at the beginning of this thread.

Then I guess we agree :D


P.S. FWIW, I know nothing of the EEC tests, but in the first 1,300 miles in my X5 35d, I've gotten between 26-28 MPG with mostly secondary highway driving. So I'm actually getting about what the US EPA ratings indicate.

The EPA ratings do seem to be a better refection of real-world consumption than the more optimistic EEC ratings. I believe that both tests use the same basic methodology but differ in detail.

Oh trust me, carmakers find ways to get around the EPA tests as well. Like installing ultra-tall, useless 5th or 6th gears to make revs as low as possible. So sure, it might be efficient for a 4-cyl sedan to operate 100km/h @ 1600rpm, but in the real world, no one will be able to accelerate or maintain speed at those kinds of revs. But a lot of carmakers do that........*coughGMToyotaHondaFordcough*.

As they always say, it depends on driving habits and road conditions. I consistently achieve closer to the EEC numbers (well, okay the extra-urban are out of reach), with my highway averages being about 10-15% above the combined cycle.

The EPA ratings still seem closer to real world results than that those created by the ECE R101 test as used in Europe and many other countries

It is more realistic only because the EPA apply a 'correction factor' to adjust the test result closer to real-world numbers. he test that it starts from has no air resistance, no air conditioning or heater, a very slow acceleration rate, and a very low 'top speed' number. Then they manipulate the result. They have been applying a 22% fudge factor for many years, but in 2008 they came up with additional correction factors (to produced what they call new fuel ratings). The issue is that the final published number goes through so many adjustments that it loses any credibility as a test result, instead being a sort of poll of what the EPA thinks the number should probably be.

Regardless of how it's arrived at, EPA figure is closer to real world than the ECE R101 result and therefore does a job better of informing consumers. That's all both figures are are intended to do. They not deigned to keep engineers happy!

All I can say is that its lots in translation somewhere as I had expected and been informed that my e70 would consume less diesel than my e53, for my type of driving, mostly around town and on b roads it most certainly does not. the salesman said it would be better the bumph suggests it does yet in the real world, for me it does not even with plastic wings and bonnet!
On a positive note the camel interior looks nice, the auto tailgate is a must and the sat nav and new idrive and apart from a ridiculous gap at the top of the glove box where I can see the hinge system the interior is a nice and comfortable place to be. So some plus points there!

As I said first up, car makers are getting better at cheating the official fuel test (ECE R101) which is the figure that your salesman would have quoted. This is not just a BMW thing.

Yes I agree. Its very concerning. I am in no doubt technology has moved on but it does make you wonder if in actual fact what is happening is car makers are just now able to make their engines emmitt low c02 at the tested levels with emmissions at untested rev ranges being of no importance. i have no idea what the c02 test involves but it does make you question what is happening.
My other interest is how they make their engines cleaner. If a car burns deisel then my logic says that no matter how you ignite the fuel it must give off the same waste gas, so in my mind a litre of deisel burnt in a X5 will give the same waste product as a litre of deisel burnt in a 1980s ford escort diesel. If that is true does the cleaning up bit just come from the exhaust?

You are right. If you burn a litre of diesel you give off the same amount of CO2 no matter what. The difference is that a modern turbo diesel makes far more power and torque from each litre of diesel it burns than a 1980s diesel. In addition modern diesels reduce emissions of particulate matter, NOx and other bad stuff via DPFs, urea injection etc

My E53 3.0d 184 pk : 11.2 l/100km
My E70 3.0d 235 pk : 11.6 l/100km

Actually, my 2005 Ford Focus has consistently gotten better than it's EPA rating.

In our 8 months of Honda Civic ownership, we could never get anything near what the EPA suggested. If you drive normally, not crazy or mad in anyway, you will get 32 US mpg (7,4 l/100km) tops. In suburban driving, it averaged more like 26 US mpg (9,0 l/100km). I think the window sticker said 30/40 which is laughable, compounded by the fact that the 5-speed auto was geared to be absolutely useless.

I think the all-time record for useless gearing for cheating the EPA is the Chevy Impala, which run 130km/h @ 2000rpm in 4th gear and had a first gear that stretched to 90km/h. :confused:

What's been your experience with Fords?

Our '02 6 Spd Vette also beats the EPA rating, regularly; especially
the highway rating...it's our "economy car".