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Question about MPG - Page 7

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Posted by Steve Pardoe on August 17, 2006, 9:57 pm


Agreed, very comprehensive and thanks for taking the trouble to post again.

It's contrary to anecdotal evidence from respected consumer organisations
and road test magazines in the UK, which have consistently stated (but
without numerical evidence) that the mileage achieved by typical drivers is
significantly worse than the 66 mpg (Imp) headline figure I've seen claimed
for the Prius.  Perhaps it's to do with the kinds of journeys we typically
make over here.

Steve (signing off)

Posted by Carpe Diem on August 18, 2006, 3:27 am

See also :

Posted by mrv@kluge.net on August 18, 2006, 1:22 pm

Steve Pardoe wrote:

Based on what I've been reading on
http://autos.groups.yahoo.com/group/Prius-UK/  , I didn't think that
there were any "respected" organizations/magazines, only entertainment

Posted by =?iso-8859-1?Q?mark=5Fdigital= on August 15, 2006, 5:33 pm

I went from Pittsfield MA and then onto MA Pike, drove 62 mph, and got 63.9

Posted by NeoPhyte_Rep on August 15, 2006, 9:23 pm

Steve Pardoe wrote:

Let me try this again.  Obviously I haven't communicated the complexity
of the control model implemented in the Prius' computers.

When you get into the Prius and turn on the system, all ancillary
devices are initially run off the traction battery.  If this were a
gasoline only vehicle, we would immediately begin consuming gasoline and
get no miles credited for it.

The Prius' gasoline engine is turned on briefly to warm the catalytic
converter.  This does not get us any miles, either, but if we haven't
wasted any time getting into motion, the converter will be warmed up by
the same engine heat used to move the car.

As we move down the road, the engine is only used when we exceed about
15 mph or the traction battery needs a charge.  If there is a down slope
and the engine is not yet running, the potential energy will be used
either to increase speed or recharge the traction battery or both,
recovering a portion of the energy used to climb the hill.  It is not
necessary to apply the brakes for this to occur.  It is merely necessary
to request less speed increase than the hill can provide.  A gasoline
only vehicle would still be consuming gasoline on this same route.

When we reach a controlled intersection and come to a complete stop, the
  gasoline engine is turned off.  All ancillary devices are run off the
traction battery.  Again, we aren't consuming gasoline to go nowhere.

It is my feeling that using an idling gasoline engine to run ancillary
devices and never recovering any energy used to climb hills is what
costs the gasoline engine only vehicle the mileage that the Prius
delivers.  The Prius is a better overall compromise of a design.  It is
the total of small changes that gains the Prius significant mileage
improvement.  What the Toyota engineers have done is make it far more
probable that a turning gasoline engine is causing the wheels to turn,
thus improving the miles for each gallon it consumes.

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