T i m wrote:
On 05 Jun 2021 23:27:11 +0100 (BST), Theo
wrote:
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With a flat 12V battery I can 'start' my Prius ...
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As an aside and knowing you like yer stats n stuff g, do you have
the real world mpg figures for *your* Prius perchance?
https://www.fuelly.com/car/toyota/prius
don't forget to switch to 'UK' units on the left side.
When I was doing ~6-10 miles each way daily commuting, with the occasional
100+ mile journey I was getting about 60mpg. Now I'm driving 3 miles each
way once a week or less, with no long journeys it's more like 50mpg. Lose
maybe 5mpg in the winter.
The main thing here is cold engine starts - on a 3 mile journey the engine
has barely got up to temperature before you shut it down again, which hurts
the MPG. It also needs to recharge my regularly-low 12V battery which is a
small additional load.
On mine it always starts the engine for a few minutes to begin with (to warm
up the cat for emissions purposes) and it can only run on pure electric up
to 42mph at which point the engine kicks in. On the 2003-9 model there's
only a 1.2kWh battery and a 20hp electric motor so, while it can do pure
electric with the engine off if you're gentle with it below that speed, most
of the time the engine is ticking along with the motor helping out when
needed. The newer models are more powerful on the electric side than mine
(the early ones were very conservatively designed).
I get how by combining an IC engine running at optimal levels with an
electric motor / battery and being able to recoup energy whilst
braking sounds like a good idea but how does all that relate to mpg
ITRW?
The usage pattern is very different from say a diesel - hybrid is best in
slow or stop/start traffic, say up to 40mph. Diesel is better at motorway
but poor for town driving. Most of my driving is 60mph+ so isn't ideal for
the hybrid, but I think the cold starts might lean a bit in favour of it.
And of course every journey starts and stops at 0mph so there's always a bit
of lower speed driving which compensates for lower efficiency blasting it
down the motorway. I would guess motorway efficiency is roughly 50mpg
unless you're behind a lorry when it can be more like 80mpg.
Horses for courses...
Theo