[Protea]

When are we the users going to stop and say enough to the manufacturers who over state the fuel economy of their cars?
My GLA 250's economy or lack of it bears no resemblance to reality. When you challenge the dealer they say well nobody takes any notice of them we all know that the manufacturers don't test them in the real world its just a guide for you to compare with other makes.
Does that principle apply to prices, the engines, the number of wheels or doors no, you get what is in the brochure, so why don't the figures tell the truth?
Well I am starting by asking Mercedes to either make my car do what they say it does or give me my money back, who else will join me?

 

[roytheboy]

I'm not saying that manufacturers are blameless in making their figures look good, and VW are certainly dishonest to criminal levels, but as you've cited the GLA250, let's look at those figures. My 2014 GLA250 brochure shows these fuel consumption figures:

Urban: 34.0
Extra-Urban: 50.4
Combined: 42.8

These are EEC Directive laboratory tests to ensure that every engine is tested in the same way (in theory and cheat devices notwithstanding), so MB are just doing what they are told to do in publishing these figures.

Speaking as an engineer, a pilot and a racing driver, as it happens, I know that there is a *vast* difference in an engine's fuel consumption over a range of revs and power demands, as well as over a range of temperatures and weather conditions, which is all to do with how much oxygen is present in the air for a given temperature and humidity. Pilots have to understand these things to a fine degree, as do racing drivers. By this I mean that you need to put your foot down harder to reach a given speed on a hot day, than you do on a cold day (I’m generalising here), which in turn uses more fuel.

Then there’s traffic: are you cruising down an empty motorway at a constant 65mph, or start-stopping and accelerating and braking your way through heavy traffic? The two environments will lead to *vastly* different consumptions.

So given all these complex factors, and the biggest one which is the differences in driving style (use of the accelerator and brake, and the ability to anticipate demands on the engine), no wonder the EEC has come up with a laboratory test for publishing figures.

So let’s look at my real-world use of fuel. I live in the sticks of North Wales so I have to drive 6 miles to my nearest shop, pub or sports facility. I do this journey a lot, always on a cold engine, and it involves a lot of hills and sudden up-hill overtakes (because I don’t like crawling behind tourists). I occasionally do a long motorway journey, but most of my journeys are very short.

After 14 months of ownership, my overall consumption is showing as 34mpg, which is exactly the same as MB’s Urban figure, and which is what I would expect my driving to relate to. Don’t forget, by the way, that the GLA250 is a quick, turbocharged, 4WD, hot-hatch designed for high performance; not a super-green city car designed for sandel-wearing tree-huggers!

So what do I get on ‘combined’ journeys? I can get 40mph without any effort other than NOT flooring the accelerator at every opportunity. 43mpg is easily achievable if one doesn’t break the speed limit, one anticipates braking (so that you don’t accelerate and then immediately brake), and one uses the cruise control where one can. I’d say this figure is spot-on.

Could I get 50mpg on the motorways (Extra-Urban)? Yes, if I sit at 65mph on a flat road in no wind with the cruise control on. Try it.

I’m sorry Protea, but speaking with experience and a bit of engineering knowledge, I won’t be joining you on your well-meaning crusade. I’m happy that MB were not trying to decive me.

 

[Protea]

Well Roytheboy, Thank you for the lecture, there are others out here also with engineering backgrounds, spent many years in motor sport and who also can fly. For your information the EEC test for the urban fuel test is set at 19 mph, the extra Urban at 39 mph. The test is run following a program causing the vehicle to change gear and increase and decrease revs. Any way well done you for getting what you get out of your car, mine gives me with a warm engine 29 mpg at a constant 65 mph. All MB can do is shrug their shoulders.Thanks for your feedback anyway.

 

[jmblack]

I've no real issue with the manufacturers - they work with the test they are given and look to compare well to competitors - except to the extent they seek to influence the test setters. It's the tests that are wholly unrealistic.

 

[roytheboy]

Well Roytheboy, Thank you for the lecture.

How rude! :frown2:

 

[sgh490]

We have recently taken delivery of a new 220d 4matic with a brochure quoted combined mpg of 56. My girlfiend drives the car most days and with 200 miles on the clock she has complained that she is getting 23-25 mpg on her daily commute. I drove it at the weekend with economy in mind and got 58mpg on a mixture of country roads and duel cartridge ways. I agree the manufacturers quoted values are in laboratory conditions but if you can achieve close to them even in the real world. On a side note I'm new to gla ownership and this forum but I'm loving both:grin2:

 

[Dan]

We have recently taken delivery of a new 220d 4matic with a brochure quoted combined mpg of 56. My girlfiend drives the car most days and with 200 miles on the clock she has complained that she is getting 23-25 mpg on her daily commute. I drove it at the weekend with economy in mind and got 58mpg on a mixture of country roads and duel cartridge ways. I agree the manufacturers quoted values are in laboratory conditions but if you can achieve close to them even in the real world. On a side note I'm new to gla ownership and this forum but I'm loving both:grin2:

That's it you see - I can accept that the tests are not 'real' world but they should be **** near close. To only get HALF the stated economy then there is something wrong!

 

[roytheboy]

That's it you see - I can accept that the tests are not 'real' world but they should be **** near close. To only get HALF the stated economy then there is something wrong!

I think sgh490's point is that it all comes down to how you drive. His girlfriend gets 23-25 mpg on a presumably start-stop commute, but he gets 58mpg on mixed roads when driving with economy in mind ...in the same car. This was my point also, even though I chose to add some other factors that might influence the figures. On my 6-mile hilly journey to the swimming pool, I can easily get 40mpg on a cold engine from my GLA250 in 'eco' mapping, sometimes better, but if I put my foot down hard in 'sport' mapping, I get less than half that.

 

[BasilD]

Much like Roytheboy and Sgh490 I get close to if not slighlty better then quoted figures in my GLA250, so no issue from my point of view.

Like has been said it very much depends on how you drive as to what you get.


Make no mistake if I hammer it the mpg goes down drastically but then it is a turbocharged car and you would expect it to do this.