Fuel Economy

  • Thread starter Thread starter Alex1975
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Alex1975

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Hi All,

The last few months I have been being very careful with my right foot, more as an interest thing than anything. I usually drive like a nutter as I am always in a hurry. It started as a game and is now actually saving me a lot of money per month.

Question: When going up a hill in say 5th gear with the engine asking you to change down but you can see there traffic ahead that you are keen not to race up behind and end up breaking, are you saving fuel. The engine is being staved of fuel so I think yes, but I am not sure.

I drive a 1.3 yaris petrol and am getting 47.5 MPG average out of my current tank.

Huge savings on time and fuel now the kids are on school holidays!!!
 
Driving to save fuel is a bit of a 'black art'... My old Dad was an absolute master at it... Used to drive us up the wall sitting in the back.. But he always got where he was going on time, cheaply and stress free..
 
If you coast to a stop with the car in gear, (until the last moment to prevent stalling), you are using NO fuel at all.
If you do the same but in neutral you are using fuel SO LEAVE IT IN GEAR.
Brakes are the fuel economists worst enemy.

Slime.
 
Drive Nissan Diesel Taxi Style!

Put it in 5th as early as possible and see how lightly you can press the accelerator without stalling.

Downhill, I don't know so much. I know coasting in neutral isn't fuel efficient -as modern engine management will set the "idle" in a way which uses more than just slowing down in gear with your foot off the pedal....
 
Another way of looking at it is, progressive braking, rather than using the engine to slow you down.
What's cheaper to replace, brakes, or clutch and engine?
 
The way to maximise fuel efficiency is to reduce the load on the engine as much as possible. Rather than let the engine labour in a high gear at low revs, sometimes changing down, to a lower gear allowing the engine to rev in a less laboured way is more beneficial. Tricks of the trade are to keep the vehicle in gear on overrun, minimise stress on the engine and gearbox, look further up the road reducing speed to avoid braking, and building speed slowly when approaching hills so you are able to reduce throttle when climbing the hill. Avoid rapid throttle or brake inputs, (drive like you have a fresh egg under your feet), and when cruising reduce the throttle to the point where the vehicle is on the balancing point of slowing, (typically you can reduce throttle by ten to fifteen degrees and still maintain speed). Reduce wind resistence, (keep windows closed), reduce engine load, (switch off the air con), reduce electrical load, (switch off any non essential electrics), maintain tyre pressures correctly, make sure your brakes dont bind, reduce your speed, do not use cruise control, anticipate future speed changes and make speed changes smooth.
 
I agree with most of what you say Mark, but surely it's more efficient to, not, change gear to slow down and to use progressive braking in a controlled way. As in coming up to a junction or traffic lights and just clucth and brake, before slowly coming to a stop.
Thereby reducing engine wear and economy of fuel.
 
I am getting pretty good at it, I have a short commute to work but I can get mine over 50mpg for the 12 minute drive.

When driving the 170 miles to visit my wife at the weekend I usually get 54mpg.

Not bad really but I do only drive a 1.1l two door.

I find the easiest thing to keep fuel cost down is to watch the road ahead. Just doing that alone helps you in many ways, as long as you act correctly on the information.
 
I dont change gear to slow down, when learning to drive my instructor told me a gearbox is a lot more expensive than brake pads, and being in the trade I know he was right. Driving a diesel turbo my engine is a lot more flexible than a small capacity petrol, in top gear I can drive at 25mph or 130 mph, and living in Norfolk I have very few hills to cope with. As part of my job I regularly have customers who struggle to get the expected fuel economy from their vehicles, recently I tested a vehicle that the customer was getting 32 mpg, I tested it over 300 miles and got 53 mpg. Same vehicle just different driving technique.
 
I got 50mpg driving to the lakes on Wednesday out of my 1.6 petrol Kia ceed.

Was going at 55mpg until I hit the motorway.

I use all the tricks, slowing down in gear, slowing down slowly to keep momentum etc etc


Put fuel in before setting off. It said 260miles in the tank, after a 130mile round trip it said 175miles left. I've tested this and the gauge is usually very accurate so if it says 250 you'll get 250.

Was well impressed
 
Slime said:
If you coast to a stop with the car in gear, (until the last moment to prevent stalling), you are using NO fuel at all.
If you do the same but in neutral you are using fuel SO LEAVE IT IN GEAR.
Brakes are the fuel economists worst enemy.

Slime.
Click to expand...

I've often heard that, but it sounds counter-intuitive - how does it actually work?
 
I drove a 1.3l Yaris up until last month when I got sick of the lack of space. I didn't make any conscious effort to drive economically yet still got 47mpg average over 10,000 miles. The Yaris has such a small engine that putting it into 5th at 30mph must have laboured the engine more as I got worse fuel economy doing that.
 
sfby said:
I've often heard that, but it sounds counter-intuitive - how does it actually work?
Click to expand...

When it's in gear the engine potentiometer is turning the engine over and this doesn't require [much] fuel to keep it turning as it's the momentum of the engine (flywheel being driven by the turning gear rather than when you accelerate and it swaps to flywheel turning the gear).
If you are not in gear the engine no longer has the gears turning the flywheel so it no longer has that momentum and needs [more] fuel to maintain the engine turning over independent of the flywheel turning the crank.

That's not exactly how it works as there is much more involving the control modules but it's the gist of it.
 
a shock to my system, i have changed from a BMW 320D efficient dynamics getting a minimum of 49MPG overall and over 60MPG on a run, to a Volvo XC90 diesel.

The volve is a big brute and at present i am getting about 26MPG combined! thats doubled my fuel useage! Ouch!
 
Golfmmad said:
Another way of looking at it is, progressive braking, rather than using the engine to slow you down.
What's cheaper to replace, brakes, or clutch and engine?
Click to expand...

I'm so pleased you said this.

My Dad had a go at me for using the brakes on my 1983 Escort rather than changing down gear.

My reply? "Hold on a minute, brake pads cost £15 and last about 5 years!" :)
 
It's all about choice, is it not.

Sometimes I drive for pure enjoyment (not exactly taking the car for a spin, although I have done that) but driving "enthusiastically", yes.

I could buy a 1.3 petrol or 1.5 cdti hatchback, but why? Our family 320d can manage 45 mpg, I don't want to go slower or in less comfort.

My mum had a D4-D Yaris. Not a car for travelling half way across Europe in :(
 
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