A160 Blue Efficiency - not that efficient!

[Smatt]

But, from the cluster displays, this sounds like urban slow driving- after all you are only doing an average of 19mph. Maybe on a longer cruise you would get much higher figures for economy...?

 

[Sp!ke]

My wife was regularly getting 19mpg out of a 1.4L Fiat Bravo.

We got rid of it sharpish and now she drives a comparatively lardy 2.4L Volvo S60 and on the same journeys achieves 50mpg.

What gets me is that the Volvo is in a much higher VED bracket, yet I thought there was a pretty direct correlation between fuel economy and Co2 output.

Its utter nonsense if manufacturers start to make cars designed to score artificially highly on some sort of theoretical emissions test without consideration to actual driver requirements or real world figures.

 

[A170 Blue]

My 6 week old A180 (1.7 petrol engine) is now giving around 44 MPG ............It now has approx 2400 miles on the clock.
When brand new the fuel consumption was lower due to the tight engine..........It is now beginning to loosen up!
The ECO meter which advises which gear you should be in is best ignorred untill the engine frees up as you will be labouring it a bit in the higher gears if you follow the recommendations............It gets better as the miles clock up!

I visited Devon at the weekend and at one stage was indicating 46 MPG plus.......Now that is economical and comfortable motoring!!

 

[hawk20]

I've got one of these as a courtesy car at the moment. I've been watching the mpg with interest. Bearing in mind this is supposed to be fuel efficient, and even has the (irritating to me) stop/start facility, I have to say the fuel consumption is pretty woeful. I took this pic this morning, after using it for two days' commute:

31mpg? Granted, the car is brand new, so is pretty tight, but the Mitsi Colt that we normally use for the commute returns 45mpg+ on the same journey, even my 320 manages mid twenties. Is this 'Blue Efficiency' all marketing hype?

It also has one of the hardest driver's seats I've ever sat on! After only a few miles, I'm getting a 'numb bum', for want of a better way of putting it, and being a base model, the seat base has no tilt adjustment to help matters.

I think the figures say it all. You had an average speed of only 19 mph so the traffic must have been awful and you must hardly ever have been in top gear. My brother has an A160cdi and has averaged over 60 mpg since new and that is a pre facelift, pre 'blue efficiency' model.

I found the seats in the A class excellent. But if I had sat for nearly two hours to do only 35 miles the seats would have seemed very hard indeed and I would have been very fidgety! Like watching a bad movie -the seats always seem hard. We did over 2,000 miles in a fortnight's holiday in France and down to Spain and neither of us had any problems with the seats.

Even in the A180cdi I regularly averaged over 45 mpg and over 50 mpg on a good run.

 

[wemorgan]

Its utter nonsense if manufacturers start to make cars designed to score artificially highly on some sort of theoretical emissions test without consideration to actual driver requirements or real world figures.

I've found that some cars are easier to achieve the manufacturer's stated mpg figures than others, but I don't know why. For example:

Audi A2 1.4Tdi - 15% less
Saab 93 2.0t - 15% more
Mercedes CLK320 - same as

The Audi claimed 65mpg on the combined cycle, but I struggle to get this on long mostly motorway runs. So I wonder if high efficiency cars are tuned for a narrow efficiency range?

 

[verytalldave]

I drove a new MINI Cooper Clubman D the other day......................................
Swap the tyres from the 17" to 15" skinnies and I bet you could get nearer 80 mpg once the engine has been run in.

Not quite true.........
While the lower rolling resistance would obviously help, the smaller diameter wheels would mean the engine would need to rev higher to maintain similar speeds.
Any advantage gained with the skinny tyres would be more than offset by the engine having to work harder.
Providing of course the gearing remained the same.

 

[wemorgan]

I thought that larger diameter and therefore lower profile tyres (same rolling radius) gave better efficiency, due to less side wall movement.

 

[Shude]

...the smaller diameter wheels would mean the engine would need to rev higher to maintain similar speeds.

Only if you forget to fit tyres!

Here is a nice example:

W202 sport rim is 16", tyre is 205/55/16
W202 C43 AMG is 17", front is 225/45/17 so 2mm larger rolling diameter
rear tyre is 245/40/17 which is 4mm SMALLER rolling diameter.

In this instance fitting larger wheels actually does the opposite of what you suggest!

Meanwhile attached is the figures I got from a brand new W169 A160CDI 3 years ago.

 

[LeighW]

I think the figures say it all. You had an average speed of only 19 mph so the traffic must have been awful and you must hardly ever have been in top gear. My brother has an A160cdi and has averaged over 60 mpg since new and that is a pre facelift, pre 'blue efficiency' model.

I found the seats in the A class excellent. But if I had sat for nearly two hours to do only 35 miles the seats would have seemed very hard indeed and I would have been very fidgety! Like watching a bad movie -the seats always seem hard. We did over 2,000 miles in a fortnight's holiday in France and down to Spain and neither of us had any problems with the seats.

Even in the A180cdi I regularly averaged over 45 mpg and over 50 mpg on a good run.

I hadn't done all those miles, it was delivered to my house which is 12 miles from the dealer, that's why I reset the computer and tried again, I'm sure the yound lad that delivered it didn't baby it on the way over! I've only been to work and back in it, never sat in it for more than 20 odd minutes at a time. Honestly, I (and my other half) were very uncomfortable in it.

My commute is 6 miles between two towns. Basically 1 mile in traffic, 4 miles A road at 40-50mph, then another mile in traffic, taking 20 minutes or so. Obviously a short run is never going to return optimum mpg, but it should surely be better than that around town, that is what these city cars are designed for, no? My point is, that our 4 year old Colt does the same run and returns 45mpg+, and my CLK with it's 3.2 returned mid twenties on the commute, although I don't use it for work anymore.

I left the A class at home today and took the Colt, no aches at all today. I can only assume the seats are designed for people with more generously proportioned backsides...

 

[hawk20]

I thought that larger diameter and therefore lower profile tyres (same rolling radius) gave better efficiency, due to less side wall movement.

No. You can see from the MB website that larger wheels with lower profile tyres (to keep the same rolling radius) have higfher CO2 emissions and of course worse fuel economy. They also aquaplane more easily, give a worse ride, wear out faster and cost more. The silliest fashion for years IMO.

Smaller wheels come with deeper tyres to give the same rolling radius otherwise the gearing, speedo etc would all be out. They are therefore much less prone to curbing damage.

 

[wemorgan]

No. You can see from the MB website that larger wheels with lower profile tyres (to keep the same rolling radius) have higfher CO2 emissions and of course worse fuel economy.

I imagined this was due to larger wheels also typically being wider too and it was the width that increased the rolling resistance.

 

[LeighW]

They also aquaplane more easily, give a worse ride, wear out faster and cost more. The silliest fashion for years IMO.

Why would a lower profile tyre aquaplane or wear out faster than a 'normal' equivalent, assuming the same width and rolling radius? I'd be genuinely interested in any proof of this.

 

[hawk20]

Why would a lower profile tyre aquaplane or wear out faster than a 'normal' equivalent, assuming the same width and rolling radius? I'd be genuinely interested in any proof of this.

They aren't normally the same width. They are wider (presumably to get a similar volume of air in them for loading and resistance to bumps etc). Narrower tyres cut into water (or mud) as a sharp knife would more easily than a blunt one, while wide ones float like a boat. Several motoring journal tests have shown the aquaplaning problem. Any 4x4 owner who goes seriously off road knows that low profile tyres are useless. The worse ride is largely I think due to the much stiffer walls needed on tyres where the wall depth is very shallow. If not you would keep banging the alloy. IMO motorists are forgetting what tyres are for. And fashion is taking cars that engineers spent years perfecting the ride for 16 inch wheels and ruining them with 17/18 or even bigger wheels -all just to look like a kid in a Nova.

Alloy wheels used to be a luxury and exclusive. Now the only exclusive thing would be to insist on standard sized steel wheels!

 

[Sp!ke]

Big wheels and fat tyres will also be heavier than skinny alternatives. Think of them as a flywheel... the heavier the wheel the harder it is to start turning and to increase or decrease rotational speed, hence increasing fuel use. They also add to unsprung weight.

Fatter tyres only help on dry tarmac road surfaces where the width of the tyre helps with cooling and tyre wear, allowing you to run a softer , grippier compound. Contact patch sizes don't have a direct link to grip at all and don't even come into the scientific equation of coefficients of friction.

 

[LeighW]

They aren't normally the same width. They are wider (presumably to get a similar volume of air in them for loading and resistance to bumps etc). Narrower tyres cut into water (or mud) as a sharp knife would more easily than a blunt one, while wide ones float like a boat. Several motoring journal tests have shown the aquaplaning problem. Any 4x4 owner who goes seriously off road knows that low profile tyres are useless. The worse ride is largely I think due to the much stiffer walls needed on tyres where the wall depth is very shallow. If not you would keep banging the alloy. IMO motorists are forgetting what tyres are for. And fashion is taking cars that engineers spent years perfecting the ride for 16 inch wheels and ruining them with 17/18 or even bigger wheels -all just to look like a kid in a Nova.

Alloy wheels used to be a luxury and exclusive. Now the only exclusive thing would be to insist on standard sized steel wheels!

But you said lower profile tyres aquaplane more? We all know that a wider tyre will be more prone to aquaplaning, all other variables being equal, pretty simple physics really. What about the faster wear rate you mentioned?

Anyhow, many modern cars are designed to run on these lower profile tyres that they come with, so surely suspension rates etc will be specified for this? Our Colt has 16" wheels with 205/45/16 tyres from the factory, and it's only a little runabout. I'm just about to replace the front tyres at 25k miles, not a terrible wear rate.

 

[Sp!ke]

What about the faster wear rate you mentioned?

Anyhow, many modern cars are designed to run on these lower profile tyres that they come with, so surely suspension rates etc will be specified for this? Our Colt has 16" wheels with 205/45/16 tyres from the factory, and it's only a little runabout. I'm just about to replace the front tyres at 25k miles, not a terrible wear rate.

Faster wear rates because the low peofile tyres generally have softer rubber amongst other factors.

Suspension alterations cannot make up for more unspring weight.

 

[LeighW]

Faster wear rates because the low peofile tyres generally have softer rubber amongst other factors..

Do they?

Suspension alterations cannot make up for more unspring weight.

They can compensate for the lack of give in the sidewall to improve ride quality though.

 

[Robbo]

It's not diesel, it's petrol. It's pretty gutless too, our 1.1 Colt feels as quick, and that only has 74bhp!

Yes I know its a diesel. my point was that it should give much better mpg than our petrol A class.

 

[J400uk]

Never been in a Classic spec A-Class, but the Artico seats in the Avantgarde are fantastic IMO. Very supportive and comfortable. They are a little firm, but not in a bad way.

there must be something wrong with it. Our petrol engined W169 can easily get over 40 mpg, so the diesel should better that.

Agreed

12k mile A150 here (same engine as the A160 Blue Efficency) and gets 30mpg minimum in town, and averages about 45mpg on a longer run. Has bigger than standard wheels and no stop start nonsense. I don't think its fantastic economy, but its better than what a 1.6 Golf or A3 with the same sort of power would achieve.

It's not diesel, it's petrol. It's pretty gutless too, our 1.1 Colt feels as quick, and that only has 74bhp!

They have probably changed the gearing on the Blue Efficency models which makes it feel slower. Anyway the Colt has a kerb weight of about 930kg and 74bhp, and the A160 has a kerb weight of 1225kg and 95bhp, so in terms of actual power to weight ratios they are equal.

 

[Bishy]

That is poor we run several renault Megane turbo diesels at work...I hate the bloody things BUT they all average over 50mpg no matter how you seam to drive them, worst ive seen in the fully loaded 150bhp diesel one was 45mpg and I wasnt hanging about!! so that mercs shocking!!!