Author Topic: driving versus speed/gears  (Read 362 times)

Jean

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driving versus speed/gears
« on: Apr 13, 2019, 10:44:05 AM »

This is a long shot - does anyone here know the answer to the following:-
Driving at 30 MPH in 4th Gear or driving at 30 MPH in 2nd gear - is there any difference in the petrol consumption - same car/conditions both times
here's hoping for a response

Dayjo

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Re: driving versus speed/gears
« Reply #1 on: Apr 13, 2019, 10:50:42 AM »
Fourth gear, consumes less petrol. As the engine is "breathing", fewer times per minute......
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StephenM123

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Re: driving versus speed/gears
« Reply #2 on: Apr 13, 2019, 11:04:24 AM »
It very much depends on the car and the gearing. In fourth it may be outside the optimum rev range making it thirstier and unresponsive. Often third would be more appropriate.

My Goldstar motorcycle had to be traveling at over 30mph before I could change up to third. In fact it was a nightmare around town as it's high gearing meant loads of clutch slip to just move off. Great fun on the far quieter A and B roads in those days! :)

Diasi

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Re: driving versus speed/gears
« Reply #3 on: Apr 13, 2019, 11:19:52 AM »
It also depends on the gradient of the road so there's no 'one size fits all, answer.
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Coastal

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Re: driving versus speed/gears
« Reply #4 on: Apr 13, 2019, 11:20:18 AM »
In most cases and at any speed it's better and more economical to drive in the highest possible gear, (providing it's not making the engine struggle and it's not the type of road that requires constant gear changing) this results in lower engine revs, less fuel consumption and less wear and tear on the engine.
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mick607

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Re: driving versus speed/gears
« Reply #5 on: Apr 13, 2019, 02:59:11 PM »
More revs equal more fuel used.

Jean

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Re: driving versus speed/gears
« Reply #6 on: Apr 13, 2019, 05:57:08 PM »

Thank you all who came back with answers
love Jean
 

StephenM123

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Re: driving versus speed/gears
« Reply #7 on: Apr 13, 2019, 07:35:21 PM »
Earlier I suggested that third gear was the most appropriate gear in  30mph limit. It seems the IAM (Institute of Advanced Motorists) agree:

https://www.iam-bristol.org.uk/index.php/articles/associate-s-guide/27-gears-using-lower-gear-at-30mph

mick607

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Re: driving versus speed/gears
« Reply #8 on: Apr 13, 2019, 07:40:24 PM »
That depends entirely on the vehicle, engine size etc. make a big  difference also number of gears, 3,4.5.6 etc.Three speed automatics will use more fuel than a four speed auto box.

Ashy

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Re: driving versus speed/gears
« Reply #9 on: Apr 13, 2019, 07:51:29 PM »
Another point is what speed you were going at before and after. Dropping from say 40mph to drive through a small village unless climbing a steep hill, one would probably stay in the higher gear, whilst the opposite would also apply.
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Diasi

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Re: driving versus speed/gears
« Reply #10 on: Apr 13, 2019, 08:08:59 PM »

Quote:"Third gear is a very flexible gear in modern cars, including diesel cars, and it’s the ideal gear when you need to keep your speed to 30mph or under.  The IAM has a simple maxim.  ‘Get the correct speed for the hazard – then get the correct gear for the speed’.  At 30mph that gear should always be no higher than third!
In built up areas Advanced Drivers will often be in second gear at 30mph."

I think I'll stick to driving non-advanced.

I just set the speed limiter to 30 mph & use 4th gear.

When I did a test recently I found that:

At 30 mph in 3rd gear my mileage drops by up to 5 miles per gallon.

At 30 mph in 2nd gear the engine's screaming it's head off & my mileage drops by up to 10 miles per gallon.
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mick607

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Re: driving versus speed/gears
« Reply #11 on: Apr 13, 2019, 09:15:07 PM »
That reminds me of a ride in my brother's car years ago, his car was a BMC Maestro 1.3 with a four speed manual gearbox.driving down the motorway with the engine screaming for mercy, I said to him for "For Christ sake change up a gear" He replied he was touching fifty mph & was already in TOP gear !   ;D ;D ;D

Dayjo

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Re: driving versus speed/gears
« Reply #12 on: Apr 13, 2019, 09:19:56 PM »
While driving my Jazz auto at 30mph, on a level road. Pulling the left gearchange paddle, drops it into 4th gear, (out of seven).

Therefore, it always selects fifth gear. I guess, Honda never read the instructions!
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Coastal

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Re: driving versus speed/gears
« Reply #13 on: Apr 14, 2019, 12:31:42 AM »
Everyone has their own style and habits when driving, I for example use the gears to slow down (probably due to the uncertainty about the reliability of the brakes on some of my earlier cars) whenever I approach a 30mph zone I ease off and drop it into 4th gear, no braking needed if you time it right, and I'm also a prolific user of indicators, a habit that some seem allergic to.
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zoony

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Re: driving versus speed/gears
« Reply #14 on: Apr 14, 2019, 12:53:49 AM »
I agree about the non-signalers but I don't see that a lot. I do expect to be acknowledged for courtesy and swear at offenders just as I get annoyed when I'm waiting to be let out of my road, which is at traffic lights, and, despite me indicating right, people slow for the lights and stop in front of me, blocking my exit, staring stonily forward while waiting for the lights to change. I swear at them much more.
When driving I habitually short-shift and use my gears rather than brakes on corners I know. Nothing nicer than a well-taken bend. ;D  (As the plumber said to...)
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