Quote:
Originally Posted by ngcles
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Hi Les,
Thanks for the response but I see you are confused.
The graph shows speed versus energy consumption per mile.
They state :-
Quote:
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Originally Posted by Tesla
Many variables affect the actual range experienced by our drivers. Here is a summary of how a small selection of these factors affects vehicle range and their relative impacts.
Vehicle Speed
Sustained high speeds have the most dramatic effect on driving range, as the first graph above clearly shows. This is because aerodynamic resistance increases with the square of speed, requiring higher forces to push the air out of the way.
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In a nutshell the graph shows that the faster you go the more energy you use.
There is nothing new here. We are all familiar with exactly that with
our petrol driven cars. The faster we go, the more fuel we use.
So why do we go faster? To get there quicker!
For example, we know if we were to drive from Sydney to the Gold
Coast for a holiday that if we were to drive at an average speed of
100km/h that we will use more petrol than we would if only doing an
average speed of 50km/h.
But we arrive in half the time.
As Tesla says, the drag of a vehicle goes up with the square of the speed.
I know you watch F1. As you are aware, since in-race refuelling is no
longer permitted, you get some drivers conserving petrol by "lifting
and coasting". In order to ensure the range of the car will be enough to
complete all the laps to the end, sometimes drivers are forced to drive
a little slower.
Anyway, so far, so obvious.
However ...
Quote:
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Originally Posted by ngcles
Little or no braking means the batteries are not being recharged via energy recovery which worsens the "all-round" consumption figure.
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No. It means that when driving in stop/go conditions that the range
would be further than it would be if your car did not have an energy
recovery system.
Your logic is back-to-front.
In a topsy-turvy world where such logic
held true, one would then go further by intermittently braking whilst
driving along the highway, which clearly is a nonsense.
I believe one of the sources of your confusion might be where Telsa state :-
Quote:
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Originally Posted by Tesla
In contrast slower city driving speeds are more efficient and electric
vehicles have a unique benefit in stop and go, low-speed driving due to
regenerative braking
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They are saying with an electric vehicle you are using less energy
in a city typically because you are driving more slowly. This is also
true of a petrol driven car when it is not stop/start. Then they go onto
say that not only do you conserve energy by driving slowly but that
in stop/go conditions, in addition to that, you have the benefit of
energy recovery.
They are not saying you will get more range by stop/go than you would
compared to just go.
However, the real bottom line is the figures they provide in the first
document I cited.
For example, for their model 85D in the year 2014, it had a quoted range
of 295 miles at 65 mph on a highway and 270 miles in a "EPA 5-cycle
Range" standard, which is a metric of slow, medium and fast driving.
Your final point with regards fitness for purpose across all demographics
as the state of the art of the technology stands today and its level of
deployment, everyone understands.
But for the well-heeled, perhaps retired, country gentleman or lady
who goes from the homestead an hour into town and back now
and then, the choice is there. The decision for people such
as that is not the Tesla versus the Hilux. They are contemplating
the Tesla versus a Porsche Cayenne or possibly even a Ferrari.
They are seeking a little bit of an adrenaline rush cross-multiplied
with some class.
It is early adopters that help drive the price of the technology down.
It was not that long ago that computers costs hundreds of thousands
and millions of dollars.