On 23/12/2011 10:33, Dave Plowman (News) wrote:
In article
,
wrote:
But what speed do you set that at? That's the exact problem with the
Pious. The engine is tuned to run best at a particular speed. Exceed
the power it produces at that and it becomes horribly inefficient.
Drive slowly and with economy in mind and it can produce quite good
results. As, of course, can most other cars of that size. Load it up
and drive it a bit harder - like keeping up with the traffic on a
motorway hill - and it becomes far less economical than a conventional
car. As well as being a pain in the arse to drive.


You are missing the whole point. It is not a plug in hybrid in the
previous sense.

No I'm not. If you run an engine at a steady speed it produces a given
maximum amount of power. That can either be used to charge a battery or
drive the vehicle direct. If it is set to provide the maximum power
required for driving the vehicle direct, it will be horribly inefficient
when that maximum power isn't needed, if the battery is full.

Can't you just turn the IC engine off and run on the batteries for a bit
- then turn it back on for a recharge?


The engine is not mechanically connected to the drive train. It's
like an electric car but you carry round a petrol generator to charge
the battery when required. Engine runs at constant speed.

Generator sets are horribly inefficient at low power outputs. If they were
very efficient at all times everywhere would generate their own
electricity.

Regeneration recovers potential and kinetic energy and stores it in
the battery.

Must be fiendishly complex, heavy and expensive.
It is an attempt to cover all bases.

Like all these things it is designed to get round US emission regulations.
With all the usual hype about performance and economy which is proved to
be a lie in practice.


That may well be true. If they were really aimed at our market they'd
use diesels with F-off big turbochargers (lag not being an issue)
instead of petrol.

Andy