Fuel consumption problems

[John Laidlaw]

Funny how much prejudice there is against Lexus. Our LS400 was a brilliant car, even at 14 years old.

Exactly, nothing wrong with a Japanese Mercedes

 

[grayb]

They are only jealous because you have a car that doesn't break down like Mercedes do on a regular basis.

LOL, perhaps. We bought it at 13 years old and 135,000 miles for £1400, ran it for a year and another 9,000 miles, and then sold it... for £1400. Nothing went wrong at all. I drove from Kent to Leeds and back and felt more rested at the end than I did when I started. I would have another if they made an estate car.

 

[LostKiwi]

LOL, perhaps. We bought it at 13 years old and 135,000 miles for £1400, ran it for a year and another 9,000 miles, and then sold it... for £1400. Nothing went wrong at all. I drove from Kent to Leeds and back and felt more rested at the end than I did when I started. I would have another if they made an estate car.

My Mercedes must be a rarity then. Bought it for £600 18 months ago with 112k on the clock. Its now on 142k and has had no issues other than what were known about at the time (crank sensor had failed, LCD display pixels out - all fixed for under £100). Its still on the same discs and pads even!

 

[Submariner1]

Well it was £25 + vat just for the diagnostics report then £20 to teach the injector valves he said he was charging me an hour's labour basically. Wouldent mind but once plugged in comp does the work. Although im glad they did it would just liked to of been asked about the extra charges before they started the started the work. But late for me to say no once they alread ran the programme to do it.

Just read this ..
I think that was an excellent result, and superb value for money.
Blimey of you had taken that to our MB garage, it would have been £175 just to tell you what the problem was and more to then fix it.
I also think all decent MB I dys would have charged your £60-70 to fix that.

Just take the incoice to the selling garage and make them pay you.
Total cost £0

 

[BClassChris]

Ok so having just sat an Eco Driving course as part of my job there are a number of pointers I have been given that have seen me increase my MPG by 10 even on these cold shitty days.

1) Lighter on the throttle when setting off - who gives a **** about the people behind you as long as you go on green
2) Minimum idling - idling kills off your MPG as said before your doing 0MPG at this point but burning diesel
3) Cruise Control - Love it or hate it set your cruise control 1-2 mph below speed limit and see a difference - in urban areas where safe to use, use it
4) Eco Roll - MB Trucks have it so maybe the new cars do too - using the autobox assuming its an auto let it decide the gears on the way down and up and down hills sometimes it will even select neutral or "E" basically this is good coasting because the car is in control of the momentum of the vehicle (as set by your cruise)
5) Interact with the car - sounds like your talking to it, no your helping it see the road and what it cant see so if your chugging away on a road with no reason to drop into auto pilot check your revs 1500 revs uses more fuel than 1200 revs over the distance and volume of fuel tank hence less mpg click up a gear and let the torque of the engine pull the car
6) Planning - As we all know plan ahead will help you see and overcome hazards in plenty of time it also allows you to anticipate what other road users are doing - we were all thought that we should look a couple of car lengths up the road when learning to drive keep on with that & you wont need to brake as much
7) Braking & Overrun - use your brakes only when nessecary otherwise your only wasting all that energy spent to get yourself going by turning it from kinetic energy to heat (wasteful) energy - The overrun is a combination of planning well ahead and allowing yourself time to let the car loose its own kinetic energy before you have to stop - by not making unnessecary stops youll get more MPG as you wont have a fuel defcit to pay when you get going again
8)Air pressures - make sure that the tyres are inflated to the correct pressures an underinflated tyre uses more fuel to move it & an over inflated tyre can be just as bad to a point
9) Tyre tread - check these regularly to avoid penalty but also a good tread provides more grip and less rolling resistance than a tyre with less tread
10)Engine care - a good tune up of the engine filters good quality fuel etc will not only prolong the life of the vehicle but also mean a healthier looking wallet too

Try these pointers out before looking at expensive servicing costs as a slight change in driving style can yield savings overall - you wont see them straightaway but a few tanks of juice later I reckon you will

 

[Craiglxviii]

The trouble with minimum idling is that, if using eco start- stop on the smaller engines this kills your timing chain...

 

[John Laidlaw]

Hmmmm...interesting economy pointers..let me give those some thought

 

[Craiglxviii]

Hmmmm...interesting economy pointers..let me give those some thought

Yup, make sure to check your tyre treads John!!!

 

[John Laidlaw]

Yup, make sure to check your tyre treads John!!!

What tyre treads?

 

[EmilysDad]

Hmmmm...interesting economy pointers..let me give those some thought

Have you thought yet? .....

 

[John Laidlaw]

Have you thought yet? .....

Yip.....not doing it

 

[Craiglxviii]

My CL’s fuel efficiency chart...

 

[BClassChris]

The trouble with minimum idling is that, if using eco start- stop on the smaller engines this kills your timing chain...

Yes I would agree with this too

 

[LostKiwi]

2) Minimum idling - idling kills off your MPG as said before your doing 0MPG at this point but burning diesel
3) Cruise Control - Love it or hate it set your cruise control 1-2 mph below speed limit and see a difference - in urban areas where safe to use, use it

I'd take issue with both of these....
Idling is a judgement call. If you sit for prolonged periods then yes switch off but every time you start your engine you need to replenish battery charge which increases engine load and consumption. This is especially true when its hot and you have aircon as the aircon also has to do more work to cool the interior of the car down. As Craig mentions it also increases wear on timing chains and wear in general as when the engine is stopped it has zero oil pressure and you then go and spin it to restart... They estimate 90% of all engine wear occurs in the first minute after starting.

Cruise can be useful on flat ground but in hilly areas it can increase consumption for the smple reason it cannot see the downhill you are on now is followed by an uphill. It will then try to slow the car on the downhills and accelerate to maintain speed on the up hills. Far better in these circumstances to disengage cruise and allow it to speed up on the downhill and slow down on the ups - conservation of momentum is the best way to improve fuel consumption.

 

[BClassChris]

I'd take issue with both of these....
Idling is a judgement call. If you sit for prolonged periods then yes switch off but every time you start your engine you need to replenish battery charge which increases engine load and consumption. This is especially true when its hot and you have aircon as the aircon also has to do more work to cool the interior of the car down. As Craig mentions it also increases wear on timing chains and wear in general as when the engine is stopped it has zero oil pressure and you then go and spin it to restart... They estimate 90% of all engine wear occurs in the first minute after starting.

Cruise can be useful on flat ground but in hilly areas it can increase consumption for the smple reason it cannot see the downhill you are on now is followed by an uphill. It will then try to slow the car on the downhills and accelerate to maintain speed on the up hills. Far better in these circumstances to disengage cruise and allow it to speed up on the downhill and slow down on the ups - conservation of momentum is the best way to improve fuel consumption.

I’m not sure what it’s like with cars but with trucks they have soft cruise which does exactly what you are saying and instead of dumping fuel into the engine to get it going it gradually does it. Also you can bypass this issue of fuel dumping like you say by interacting with the vehicle and using your head because like you said there will be circumstances where the vehicle will get it wrong.

In the end it’s all about using your head and planning ahead to save excess fuel usage


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[oigle]

Cruise can be useful on flat ground but in hilly areas it can increase consumption for the simple reason it cannot see the downhill you are on now is followed by an uphill. It will then try to slow the car on the downhills and accelerate to maintain speed on the up hills. Far better in these circumstances to disengage cruise and allow it to speed up on the downhill and slow down on the ups - conservation of momentum is the best way to improve fuel consumption.

Absolutely correct. Cruise will never be more economical than a well driven vehicle under manual control. Amazes me that many people just don't realise that.

Ian.

 

[LostKiwi]

The other thing about cruise is the way it constantly adjusts the throttle.
This will use more fuel than keeping the throttle constant. Years ago we had a Fiat 132 (amazing car for the mid 70s) which had a hand throttle that could be set as a very crude cruise control. Proper use of such a thing can give better economy than either manual control or cruise. Very difficult to get right though!

 

[BClassChris]

Everyone views cruise control differently but I’ve always seen better fuel figures using it than without on the same route with the same cars at the same times of day it all depends on what type of roads it’s used on such as hills etc


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[Craiglxviii]

Everyone views cruise control differently but I’ve always seen better fuel figures using it than without on the same route with the same cars at the same times of day it all depends on what type of roads it’s used on such as hills etc

Me too. Depends heavily on route travelled but I usually expect a 5-7% improvement over manual throttle control.

 

[John Laidlaw]

Me too. Depends heavily on route travelled but I usually expect a 5-7% improvement over manual throttle control.

Depends what altitude your car likes to cruise at....