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14th November 2011, 08:15 | #1 |
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Auto or manual mpg
Autos do use more fuel but when the auto has a lockup on the top gear why is the mpg worse at motorway speeds?. Could it be the transmission ratio on the auto is lower?
Back in the 80's I had a number of Carltons and the auto on the motorway was more econumical. |
14th November 2011, 09:47 | #2 |
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How long do you have? so many things affect fuel economy.
Also, the Auto has a slightly lower top speed, could be doing a few more revs at motor way speeds that could affect it.
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14th November 2011, 10:23 | #3 |
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How do you know they have a lockup on the top gear ???
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14th November 2011, 11:42 | #4 |
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14th November 2011, 16:43 | #5 |
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In general terms a manual will always, in theory, be more economical than an automatic. A manual transmission provides a more direct link via the manual clutch from the engine to the wheels while the automatic relies on oil pressure and a fluid flywheel as a clutch between the engine and transmission to supply the drive. There is always a loss of energy because of the automatic set up which makes the manual better regarding fuel consumption.
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14th November 2011, 17:03 | #6 |
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The Auto, (in the 2.5 V6.) actually revs lower than the manual once the torque converter locks up so in theory the mpg should not be much worse, possibly a little better.
the problem is that it is very easy to unlock the auto box with very gentle presure on the loud pedal. so to actualy cruise in top with the lock on is quiet difficult, even using cruise does not really help as the minute the brain of the system demands more power (going up hill for example.) you will see the revs rise without the gear changing. Richard |
14th November 2011, 17:08 | #7 |
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A auto v a 190, well on a motor run the auto will be better as the 5 gear on my 190 has the engine revs far to high (at 70mph its just over 3000rpm).
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Previously owned- MG ZT V6 160 Y plate Lpg, MG ZT 190 2003 In Rare Celestial Factory Ordered Lpg MG ZT 190 2004 lpg Last edited by Simon.h; 15th November 2011 at 15:01.. |
14th November 2011, 21:26 | #8 |
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14th November 2011, 22:32 | #9 |
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One word:- clutch slip in effect. Sorry ,thats four. Never was good at maffs.
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15th November 2011, 00:02 | #10 |
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I seriously doubt the cars mpg are any diff in top gear, what make the op think they are?
Top speed is the same for both, final gear ratio is the same on both, so why would mpg be diff?? 2200 revs = 70 mph on my cars clock.. ... |
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