Author Topic: Amazing mpg  (Read 6353 times)

MikeG1944

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Re: Amazing mpg
« Reply #15 on: May 19, 2017, 01:54:12 PM »
I think you hit the nail on the head; driving style. I get good mpg even driving short journeys, but drive economically with slow acceleration and slow or little braking; whereas my wife does worse with a lot of acceleration and braking from fast speeds quickly at the last minute. They do reckon that you can save a lot of fuel with a careful driving style. :)
P.S. I've given up explaining this to the wife LOL!

Jocko

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Re: Amazing mpg
« Reply #16 on: May 19, 2017, 02:51:16 PM »
They say you waste fuel every time you brake, as you wasted the energy getting up to that speed in the first place. Rather a simplistic view, but worth keeping in mind. I tend to use gentle acceleration on down slopes then allow the speed to drop off on the uphill sections. Better that than going downhill on a trailing throttle then having to use wide throttle openings on the uphill bits.

MikeG1944

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Re: Amazing mpg
« Reply #17 on: May 19, 2017, 03:14:59 PM »
I do think the breaking does waste energy, and hence fuel Jocko, as otherwise F1 cars wouldn't bother using it to store the energy when braking, albeit a small amount. You are basically fighting the engine going forward by braking unless you drop the revs right down first before pressing the brake pedal (opposite of what my wife does LOL).

I think the CVT system is excellent as it selects the 'right gear' (the correct position on the cones) for the amount of torque and speed needed in Drive mode, and I doubt all but the best drivers could match that as good with a manual box. Hence it's very good mpg figures. :)

Mike.

Jocko

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Re: Amazing mpg
« Reply #18 on: May 19, 2017, 03:39:55 PM »
F1 energy recovery system gathers a huge amount not a small amount. KERS (the old system) gave 80 bhp for 6 seconds. The new system gives 160 bhp, 120 bhp from braking and the rest from exhaust heat recovery.
I remember reading a book, many years ago, about the Ford GT40's at Le Mans. At the end of the Mulsanne Straight their brake discs went from -10ºC to 1000ºC, every lap!

MikeG1944

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Re: Amazing mpg
« Reply #19 on: May 19, 2017, 03:47:36 PM »
F1 energy recovery system gathers a huge amount not a small amount. KERS (the old system) gave 80 bhp for 6 seconds. The new system gives 160 bhp, 120 bhp from braking and the rest from exhaust heat recovery.
I remember reading a book, many years ago, about the Ford GT40's at Le Mans. At the end of the Mulsanne Straight their brake discs went from -10ºC to 1000ºC, every lap!

Didn't know they gained that amount Jocko, surprising they don't use the heat from the brake disks to recover more (excuse me while I file a patent).

Mike.

culzean

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Re: Amazing mpg
« Reply #20 on: May 19, 2017, 06:54:03 PM »
They say you waste fuel every time you brake, as you wasted the energy getting up to that speed in the first place. Rather a simplistic view, but worth keeping in mind. I tend to use gentle acceleration on down slopes then allow the speed to drop off on the uphill sections. Better that than going downhill on a trailing throttle then having to use wide throttle openings on the uphill bits.

If not much traffic around I tend to coast downhill and then coast up the other side or on the flat until speed drops too much, then back into gear, that way the engine braking is not absorbing power and you get full benefit of gravity - some say it is illegal, but who is checking ???  Also engine braking cools the engine (cold air going in with no mixture to explode and keep it warm) and a cooled engine is not as efficient as a hot one.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

Jocko

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Re: Amazing mpg
« Reply #21 on: May 19, 2017, 07:07:43 PM »
SAAB's used to have a freewheel, back in the days of the 96 and some 99's. Rover had a freewheel up until 1959. On the later P4's it was engaged and disengaged by a large handle on the dashboard, not unlike a water valve!

d2d4j

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Re: Amazing mpg
« Reply #22 on: May 19, 2017, 08:22:03 PM »
Hi

A little off topic sorry, but I was gifted a car ... wortberg knight tourer (sorry if I have misspelled) in the eighties. Had to collect from dock lands London

Think lada estate but worse

That car had 3 forward gears I think and freewheeling in all gears. If you were not used to it, it was frightening approaching roundabout, junctions etc. My favourite trick was to put it in first gear at 40mph (when not touching the accelerator) haha never forget that car

Many thanks

John

Jocko

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Re: Amazing mpg
« Reply #23 on: May 19, 2017, 10:47:05 PM »
Wartburg Knight. I remember them well. Three cylinder 2 stroke. Three coils, one for each cylinder. A novelty back then.

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