C280 - 16.8mpg !!

[SpikeUK]

I am sooo glad I bought a diesel that I can afford. I NEVER consider the cost of fuel. I know it's good, and I don't want to curtail my plans or driving habits.....

 

[BlackC55]

In city traffic, you never, ever, ever, ever, need more than 1,500 RPM, this is as true of an auto box as a manual. Braking should be equally light and gentle.

Now re-define your "not that heavy footed" in the light of the above.... I suspect I could drive your car on the same route, make the same schedule, and get as a minimum 50% more mpg, maybe even 100% more.

Isn't that a bit boring though?

I drive becasue I like it and get great pleasure from it.

Fuel economy does not really bother me that much. As long as it does at least 200 miles on a tank I'm happy.

Driving sedately and not reving the engine much does no good to diesel CATS. They block up with heavy deposits of soot. A good blast at high RPM does them a world of good. The 300TD and 250TD engines are a prime example of the intake tract blocking up with gunk. Some I have seen have more than halved their pipe diameter with built up gunk due to "driving like Miss Daisy". This can't do any favours to the general effiency of the engine.

There is one C250TD that I do that is driven HARD and fast. There is virtualy no gunk in the intake system.

 

[NormanC]

if you are prepared to sacrifice some journey time, sticking to a STEADY 60 mph on the motorway in preference to constant speed changes around a mean of 80 mph will also make VAST differences to your motorway mpg.

As you say, changing your mean speed from 80 to 60 (or even 70) will have a dramatic effect on your consumption.

However, varying your speed can also improve your consumption significantly if done properly. Think of it as holding an absolutely steady throttle pedal. As you go up hill you will slow down slightly but on the following down hill you'll gain back the speed you lost plus some!! Typically, your speed could be varying from 60 to 80 (around a mean of 70mph) but this technique will get you measurably better consumption. You end up driving like the typical white van man - pass everyone on a downhill but get passed by everyone on the next uphill!

Whilst not being able to give absolute figures I believe from my own experiences that you can gain about 5-10% more mileage by letting the speed vary as opposed to keeping an absolute steady speed.

 

[PXW]

Have to confess I'm with the 'just drive it and put more fuel in when it runs low' camp. My 3 litre V6 diesel has seen over 47mpg on a long run of mixed roads - but I wasn't trying for economy (average speed on that run was 53mph).

I was idly 'channel hopping' on the on-board computer earlier today and discovered that I have averaged 30.5mpg over the last 22,000 miles (since the thing was last re-set). Happy with that, as I do like to accelerate - it's one of the few motoring pleasures left to us these days.

 

[renault12ts]

Actually, you'd be amazed what you can get out of an ordinary car.

years ago I bought the (now ex) wife a mint mk3 cortina, she hated it and said it was weedy and underpowered and drank too much fuel... (she wanted a porsche /audi 924)

to prove a point I got in the driver's seat, tucked my right foot under the front of the seat, and put my left foot over the clutch.

using nothing more than the "tickover" throttle opening we pulled away (no, not a flat road or downhill by any means, it was actually uphill) and progressed through the gears, using only the clutch pedal and when needed the brake pedal.

at times we were in top gear.

10 minutes later we arrived at her place of work, manoeuvred around the car park, and parked in her space, still having not once touched the accelerator.

instead of the 20 mpg she was getting out of the 1600 lump, that journey was nearer 50+

While I would not advocate driving down the M5 at 500 rpm in top gear, having a genuinely light foot, light braking, driving SMOOOOOOOTH, will utterly transform your mpg while not making any real difference to overall journey time...

if you are prepared to sacrifice some journey time, sticking to a STEADY 60 mph on the motorway in preference to constant speed changes around a mean of 80 mph will also make VAST differences to your motorway mpg.

In town I basically don't get above 1500 rpm, except for maybe 2 or three seconds to 1700 here and there due to the road etc, manual or automatic, english french or german car

going from A to B I don't get above 3000 rpm, usually being around 2500/2700, manual or auto, eng, fr, or ger car.

I suspect I'm getting IRO 30/35 around town with my 300d, not a light car. Getting 45/50 on a run.

SMOOOOOOTH is the secret.

Smooth is fast.

"Fast" is slow.

"Fast" is poor mpg and brake and tyre life

"Fast" is not relaxing

When teaching my daughters how to drive (on a strand) I used the clutch only method. In other words as you have said I had them move off in 1 st and into second with only the clutch and tick over. When they could do this (and thus were very gentle with the clutch) I introduced them to the throttle.

They are nice smooth drivers now.

 

[NormanC]

Isn't that a bit boring though?

I drive becasue I like it and get great pleasure from it.

Fuel economy does not really bother me that much. As long as it does at least 200 miles on a tank I'm happy.

Well said.

If it's a business journey I'll tend to look at the economy but when it's a journey for myself......

I'm a strong believer that any real engine will benefit from regular (but not necessarily frequent) use of that bit of the rev range from 5000rpm to the red line. I love my Celica running up to 7300rpm with 1 bar of boost - gorgeous!!

 

[iscaboy]

Isn't that a bit boring though?

I drive becasue I like it and get great pleasure from it.

Fuel economy does not really bother me that much. As long as it does at least 200 miles on a tank I'm happy.

Driving sedately and not reving the engine much does no good to diesel CATS. They block up with heavy deposits of soot. A good blast at high RPM does them a world of good. The 300TD and 250TD engines are a prime example of the intake tract blocking up with gunk. Some I have seen have more than halved their pipe diameter with built up gunk due to "driving like Miss Daisy". This can't do any favours to the general effiency of the engine.

There is one C250TD that I do that is driven HARD and fast. There is virtualy no gunk in the intake system.

I enjoy driving.

Boring?

If I want excitement in my life the most boring place to look for it is behind the wheel of a car on a public highway. Without wishing to be insulting I can think of nothing sadder than having to resort to driving a car on a public highway for excitement.... over half the population is female you know...

I don't have a catalyst, or under bonnet electronics, or anything else..

I should have taken a picture of my intake manifold last week, clean as a whistle, I did more or less have pictures of my exhaust manifold, a very light coating of soot, no more than paint thickness, that'll do me.

 

[st4]

I enjoy driving.

Boring?

If I want excitement in my life the most boring place to look for it is behind the wheel of a car on a public highway. Without wishing to be insulting I can think of nothing sadder than having to resort to driving a car on a public highway for excitement.... over half the population is female you know....

Lots here do find car driving exciting, you're probably speaking to the wrong bunch as most here like driving etc hence they are on a forum related to cars and DRIVING (which cars are for).

I derive huge pleasure from driving my car, we have brilliant roads up here in Scotland and quite frankly there are few things that come close to being as much as driving along them.

 

[kwakdonut]

If I had to spend my day driving in London traffic, I wouldn't use a 2.8L V6 petrol and moan about the fuel consumption!!!! The car was your choice so either live with it or change it!!

 

[iscaboy]

Lots here do find car driving exciting, you're probably speaking to the wrong bunch as most here like driving etc hence they are on a forum related to cars and DRIVING (which cars are for).

Sorry, no...

cars are transport, no more and no less.

motorcycles now.... different story...

This is my bike (www.tr1.de)

One seat, no pillion H^H^H^H excess weight, very, very, very low centre of gravity, not the fastest bike on the planet in a straight line down the autobahn, but on A roads it eats everything else (2 wheels and 4) for dust.

Like being slung down the road sitting on a tea tray.

If you don't know these, it was originally a Yamaha TR1, their "homage" to the vinnie.

If you look closely you will see there is no frame, just a scantling over the engine that the tank, front and rear suspension, and seat hang off.

Since these pix it has been powder-coated all black silk gloss, yum yum.

1,000 cc, 78 BHP, 92 Nm, 187 Kg dry.

 

[st13phil]

BTW, does anyone have access to a 2008 brochure which has the published C280 MPG figures in it ?

From the April 2008 Price List:

C280 Auto Fuel Consumption (mpg) - Urban 21.2 / Extra-urban 40.9 / Combined 30.7

 

[vtwin]

I average 20 mpg from my C43AMG on a fast run I get 315 miles from a tank (recently driving across France) and mixed driving gets me 250-260

 

[A-AvantGarde]

I think we need more information on this.

Firstly the on board trip computers aren't terribly accurate. The best gauge is the miles you can get repeatadly from a full tank. However one thing is clear, short infrequent journeys in constant stop / start traffic take their toll when it comes to fuel economy.

What sort of length journeys (time and distance) are you talking about FF99?

Out of interest, do you know what the trip computer says for average MPG from last reset (and do you know when it was last reset?) it will tell you miles and hours / mins from reset. Although it's not indicative of your driving it would be interesting to know.

The instant / real time MPG figures aren't much use.

 

[FF99]

I think we need more information on this.

Firstly the on board trip computers aren't terribly accurate. The best gauge is the miles you can get repeatadly from a full tank. However one thing is clear, short infrequent journeys in constant stop / start traffic take their toll when it comes to fuel economy.

What sort of length journeys (time and distance) are you talking about FF99?

Out of interest, do you know what the trip computer says for average MPG from last reset (and do you know when it was last reset?) it will tell you miles and hours / mins from reset. Although it's not indicative of your driving it would be interesting to know.

The instant / real time MPG figures aren't much use.

I reset the trip computer when I last filled up 70 miles ago and the 16.8 MPG figure I gave came from the trip computer. The trips are on average 5 miles at 12-14MPH, with no particular hold ups but lots of stop / go at traffic lights.

I followed the advice to go easy on the drive home tonight and tried to keep below 1500 RPM as suggested above (near impossible and I never got over 20MPH, although traffic was very light). It did take my consumption up to 21.2, which is exactly the figure given 3 posts up as being the published urban MPG. I did not realsie that the published figure was that low, so perhaps I should not be concerned; although in the real world one could not possibly drive in that way !

One thing I did wonder about is that when standing at lights the engine runs at 500 RPM, which rises to 600 if I put the gear selector into P. does that sound right ? When I start the engine it runs at 1,200 for a short but noticeable period and then drops back down below 1,000. Does that also sound right ?

 

[iscaboy]

I followed the advice to go easy on the drive home tonight and tried to keep below 1500 RPM as suggested above (near impossible and I never got over 20MPH, although traffic was very light). It did take my consumption up to 21.2, which is exactly the figure given 3 posts up as being the published urban MPG. I did not realsie that the published figure was that low, so perhaps I should not be concerned; although in the real world one could not possibly drive in that way !

OK, so you drive a vehicle TOTALLY unsuited to that sort of traffic, but even so, you take the advice given (bravo) and..

Go from 16.8 mpg to 21.2 mpg, which is over 26% better mpg right off the bat...

If you practice it, and the minimal braking, SMOOOOOTH, you boost that to 50% and get 25 mpg, for FREE.

You (we) drive HEAVY cars, every time we accelerate them it takes energy, LOTS of energy.

Every time we hit the brakes we throw away energy, LOTS of energy.

Try pushing a car 100 yards along a flat road, then you'll see just how much energy.

Also check your tyre pressures and alignment, being 5 psi out can cost 10% extra fuel.

Fact is you ought to be in an electric car with that sort of journey and traffic.

 

[FF99]

OK, so you drive a vehicle TOTALLY unsuited to that sort of traffic, but even so, you take the advice given (bravo) and..

Go from 16.8 mpg to 21.2 mpg, which is over 26% better mpg right off the bat...

If you practice it, and the minimal braking, SMOOOOOTH, you boost that to 50% and get 25 mpg, for FREE.

You (we) drive HEAVY cars, every time we accelerate them it takes energy, LOTS of energy.

Every time we hit the brakes we throw away energy, LOTS of energy.

Try pushing a car 100 yards along a flat road, then you'll see just how much energy.

Also check your tyre pressures and alignment, being 5 psi out can cost 10% extra fuel.

Fact is you ought to be in an electric car with that sort of journey and traffic.

Tyres checked early on and OK (should I be using them more heavily or more lightly pumped for fuel economy ?) and you are, of course, right that I should be driving an electirc car if I want to keep my fuel costs down . However, truth is that I want the feel of a real car. I test drove several C250 CGIs and they all seemed too 'weedy'. I can't put my finger on what it is, other than that I was told that if I was used to a 6 cylinder, I would not like a 4 cylinder.

I am not quite as daft as I seem, as I recognise that having a C280 is undoutedly a luxury and the fact is that, given my low mileage, I could quite easily afford to run a car getting only 10mpg. The point of the post was to check that the consumption was reasonable for the car I chose, not whether I chose the right car. Anyway I have picked up some useful tips and will try improving my technique, something I have never previously thought about in 40 years of regular motoring !!

A couple of final questions: I have not even begun to think about using the 'manual' gear change paddles. Would doing that nake any appreciable difference (assuming I could get the hang of them ??) ?

If anyone has any thoughts on the RPM which my car is running at, as mentioned above, I would be grateful.

Thanks to everyone for all your thoughts and help.

 

[Iain]

Should have bought a diesel Mercedes. Better suited to your needs I would have thought.

 

[FF99]

Should have bought a diesel Mercedes. Better suited to your needs I would have thought.

I tried a C250 CDI and a C320 CDI (and a BMW 320 Diesel) but I found them to be a horrible driving experience. Soooo sluggish moving from a standing start, which is what I spend half my driving time doing.

 

[Iain]

C320cdi sluggish? don't think so.
Perhaps therein lies your answer. 0-14mph standing starts will use a lot of fuel if you leave your tread on the road!

 

[FF99]

C320cdi sluggish? don't think so.
Perhaps therein lies your answer. 0-14mph standing starts will use a lot of fuel if you leave your tread on the road!

I felt that in the diesels, although the acceleration was great once the car started moving, there was a noticeable lag between touching the accelerator and getting any movement. In another thread here (or maybe on another forum) I read a recent post about someone who almost had a serious accident on a roundabout because his high power C class diesel did not start moving as quickly as he expected it to.