OT: Hybrid cars

[Mord Behar]

On Sun, Sep 15, 2013 at 7:20 PM, Oleg Goldshmidt <pub at goldshmidt.org> wrote:

> Oleg Goldshmidt <pub at goldshmidt.org> writes:
>
> > Even if your car is a plug-in there are things to consider. Take a new
> > Prius with an extended Li-ion battery with capacity of 4.4kWh. I pay
> > ILS0.54/kWh at home, so at 80% efficiency a full charge will set you
> > back about 3 shekels. At ILS8/l this is about 0.375l of 95 octane
> > petrol. Thus, if you buy petrol instead of charging the battery, at
> > 15km/l you will drive about 5.5km instead of 25km for the same money. A
> > clear win for Prius. However, consider this: a Prius plug-in is *at
> > least* ILS180K on the Toyota site, whereas a Corolla starts at
> > ILS124K. That's 56,000 difference, equivalent to 7000l of 95 octane
> > petrol (at 8 shekels/l). Let's download PDF catalogs with fuel
> > consumption data from the site. To cover the 7000l of fuel equivalent of
> > the price difference between a plug-in Prius (25.6km/l) and a Corolla
> > (17.9km/l) you need to decide whether or not you believe the 25.6km/l
> > figure (cf. [2] below). If you do, you'll break even after ~420,000km
> > [7000/(1/17.9-1/25.6)]. Convert into years for yourself.
>
> I suppose it is generally clear, but a limiting case is always
> instructive.
>
> Assume you buy a plug-in Prius and you *never* drive more than
> 25km/day. Also assume that you drive exctly 25km/day for 364 days a year
> (excluding Yom Kippur), no faster than 45km/h, and fully recharge every
> night. Therefore, you drive only on battery, and your fuel consumption
> is 0. Assume also that you work for Hevrat Hahashmal and the electricity
> is free. This is, obviously, the best possible case for a plug-in
> hybrid.
>
> Your "null hypothesis" is a car that gives you 17.9km/l (a petrol Toyota
> Corolla or equvalent), that costs 56K less, the difference equivalent to
> 7000l of 95 petrol at today's high prices. At this level of fuel
> consumption you need to drive 125,300km in your Prius to justify the
> price difference. Since you drive 9100km/yr (25*364) it will take you
> almost 14 years to break even. Again, this does not take into account
> the TCO, or the interest that your 56K would earn over 14 years if
> invested, or anything but the purchase price difference.
>
> I cheated, of course: the 17.9km/l is a mixed city/highway number. For a
> fair comparison under the assumptions above we need to take the city
> consumption for the Corolla as well. A quick google yields a value of
> 9.6km/l for a 1.8L Corolla - that is almost twice as bad as the mix
> value. We get 67,200km, or just under 7.5 years to justify a plug-in
> Prius under our assumed - and extremely beneficial - conditions.
>
> Please note that none of the above should be misconstrued as any kind of
> put-down for Prius or hybrid cars in general - they are just overpriced
> (IMHO). Plug in the real quotes for your own estimates, of course.
>
>
Wow. Thank you for that, it was quite informative.
You mentioned that small petrol European cars have a 20 km/l range. Right
now I'm driving a Fiat Panda. It's small and it's efficient, but it comes
at a price. The engine is tiny, and so is the gas tank (but being a tiny
car it's easy to park in the city). The book says that it can get 20 km/l
intercity, and 12 km/l in the city. From my experience I get 18-19 on the
highways, and 10-11 in the city. But that's probably my fault. It's a
manual shift and I am not the most efficient shifter. I do better on the
highways than in the city.
So the figures you used are clearly for highway driving, where the increase
in fuel economy is the greatest, across the board. But what about smaller
commutes? Errands run in the city? My gut tells me that it will be a lot
harder to break even if 85%-90% of the time spent driving is done in the
city (even if the majority of the kilometers driven is on the highway).


> --
> Oleg Goldshmidt | pub at goldshmidt.org
>
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