Fuel economy improvements this century

[Dewi 2]

I don't often talk about fuel economy, because unless we drive high mileages, depreciation remaims the expensive part of owning a car.
The motor industry never like to speak about that. -

Here is one example of an improvement.
Two cars with (coincidentally) identical acceleration and top speed performance.
Motorway journey petrol consumption figures.

2000 CLK 320 ......... = 35 mpg
2022 E200 ............... = 55 mpg

The improvement is obviously achieved by the smaller engine and using a turbocharger.
Think the engine speed at 70 mph might be lower, but not sure about that.

I do prefer the quieter V6 engine of the CLK, but a 6 cylinder option was not available in the UK for W213s.

[MustangGT]

I think the E200 is a mild hybrid so not totally reliant on the petrol engine. According to Honest John the real life mpg of a 2022 E200 petrol is 28.6 mpg. The diesel version is around 52.9 mpg. Are you mixing the fuels up?

[Dewi 2]

MustangGT said:

I think the E200 is a mild hybrid, so not totally reliant on the petrol engine.
According to Honest John the real life mpg of a 2022 E200 petrol is 28.6 mpg.
The diesel version is around 52.9 mpg.
Are you mixing the fuels up?

On the move, all that the electric motor does with regard to propelling the car, is provide an extra boost to fill in for turbo lag.
Rarely ever needed on a motorway journey, so we are really comparing two petrol only cars.
My post was just in reference to motorway journeys, so obviously that would be a best achievable mpg figure.
Likewise the CLK figure, hence a like-for-like comparison to notice that considerable improvement in 20 years.

Honest John would be providing an overall mpg figure.

If the diesel version gives 52.9 mpg overall, then it would achieve a huge number of miles on a long motorway journey.
I expect that is precisely the reason, why most E Class cars are still diesel powered. I had to wait ages for a petrol to appear on sale.

For me, one unexpected aspect of 'mild hybrids' (cannot move the car), is that at MoT time, no emissions test is required. I asked for the usual print out of figures and was then told.

[SL222]

The mild hybrid system really just allows the engine braking to recharge the battery and then release the excess power when you accelerate, and it lets the engine cut out in glide mode. It won't drive on electricity alone.

My E220D gets 50-55mpg on long runs (which is all I ever really do) so I'd be very surprised if the petrol version gets anywhere near that. I reckon it makes 5% - 10% difference to the mpg.

[Dewi 2]

SL222 said:

The mild hybrid system really just allows the engine braking to recharge the battery and then release the excess power when you accelerate, and it lets the engine cut out in glide mode. It won't drive on electricity alone.

My E220D gets 50-55mpg on long runs (which is all I ever really do) so I'd be very surprised if the petrol version gets anywhere near that. I reckon it makes 5% - 10% difference to the mpg.

The journey that I quoted (done frequently) is;
initial 1 mile on town roads,
170 miles continuous motorway (under 70 mph),
then 1 mile on a country road to destination.

That is obviously going to give a higher mpg than any other type of journey, but if the 55mpg figure is wrong, then it is the MBUX system that is wrong.
My point was simply to point out the considerable improvement over the 20 year old MB, which did exactly the same journey when the trip read out showed 35 mpg.

I would have thought your E220D would do better than 55 mpg, if you did the 170 plus 2 miles journey, which I have described.
If a greater proportion of that journey was non motorway, then of course it would soon reduce the average mpg.
I think the engine revs at a constant 68 mph, are only about 1,600 rpm in 9th gear.
Interestingly, MBUX shows the engine is only producing 20 bhp, to propel the car at a constant 68 mph on a level section of road.

I don't use start/stop or glide, but that is another story.

[MustangGT]

I have had a C class mild hybrid (2016) which had the 2.1 diesel. The hybrid system primarily acts as a range extender that allows the engine to shut off when the battery has charge and the motor can provide enough power. I averaged just over 60mpg compared with 54 mpg in a non hybrid version. It would just move the car under electric alone, such as on the driveway.

I would agree that, overall, if cruising sub 70mph on a level motorway you should get really good figures from any powertrain, but would argue that is pretty irrelevant overall.

I also agree that advances have been made with both petrol and diesel engines recently, e.g. a 2014 Dacia Duster diesel 4x4 would achieve around 45mpg overall, the 2022 version with the same base 1.5 Renault diesel achieves around 55mpg. AdBlue was added to that fuelling system in 2019.

Petrol improvements are generally achieved by downsizing and adding forced induction. This helps by reducing internal losses with the smaller size, less fuel used at tick-over etc. Really great achievements.

[SL222]

Dewi 2 said:

I would have thought your E220D would do better than 55 mpg, if you did the 170 plus 2 miles journey, which I have described.
If a greater proportion of that journey was non motorway, then of course it would soon reduce the average mpg.
I think the engine revs at a constant 68 mph, are only about 1,600 rpm in 9th gear.
Interestingly, MBUX shows the engine is only producing 20 bhp, to propel the car at a constant 68 mph on a level section of road.

I don't use start/stop or glide, but that is another story.

Yes I'm sure you're right, I may occasionally stray over 71mph - very hard to compare apples for apples in this situation. I have seen over 60mpg when driving v slowly behind a lorry. Hats off to you for your parsimonious driving style and 3 cheers for more efficient engines.

[TarquinMX5]

Aerodynamics have improved over the years and lower rolling resistance tyres also have an impact, particularly at motorway speeds. As an aside, I was surprised that the Range Rover (proper one) now has a Cd of 0.3. The E-type, which many thought was very aerodynamic, was 0.5, a huge difference.

[Dewi 2]

SL222 said:

Hats off to you for your parsimonious driving style and 3 cheers for more efficient engines.

Thank you.

The reason for my adherence now to (sometimes ridiculous) speed limits, is to do with insurance premiums.
If insurers decide to load a premium, following (say) some minor driving prosecutions, the loading will be applied to every motor insurance policy that we have and it will continue for 5 years, not 3 years which I think is the duration of penalty points.

Anyone with a small car collection would be really clobbered. Imagine £50 premium loading x 5 years x 6 cars.
£100 speeding fine, plus £1,500 to the insurance industry.

An ideal car, which seems to encourage gently wafting along, is the E Class, so it is no hardship to dawdle through long stretches of straight deserted roads, obeying the 20 mph speed limit. I understand the speed traps are set to 24 mph. Best if you are retired though, with plenty of spare time available. Set the cruise control, relax and talk to the Hey Mercedes lady.
Have any of you teased her, by asking, "Do you like BMWs?"
She is ready for that question.

[Dog Star]

Dewi 2 said:

Thank you.

The reason for my adherence now to (sometimes ridiculous) speed limits, is to do with insurance premiums.
If insurers decide to load a premium, following (say) some minor driving prosecutions, the loading will be applied to every motor insurance policy that we have and it will continue for 5 years, not 3 years which I think is the duration of penalty points.

Anyone with a small car collection would be really clobbered. Imagine £50 premium loading x 5 years x 6 cars.
£100 speeding fine, plus £1,500 to the insurance industry.

This is so true - especially motorbike insurers absolutely have a cow if you have points or a claim. I had a car claim back in 2016 and that really never bothered my car insurers. Motorbike insurers on the other hand…. (Which is odd, as motorbike insurers won’t recognise car NCB but take a great deal of notice of a car claim..)

I, like Dewi, simply don’t speed. The limits are often ridiculous but that’s how it goes. But I do quite well on fuel, my SL 350 gets 35mpg or more on a run.