Update on Prius MPG

: Back when the car was new, in the dry, warm August weather, I was : getting around 58mpg. As the weather cooled and became generally : misty, I had to run lights and demisting equipment (a/c, blowers, : rear window heater) more and the figure fell to 51.2mpg.

In the U.S. more depends on the region you live in. If you live in California, your mileage will be dramatically less than the rest of the nation due to the mix of the fuel (clean air laws regulating the formulation such as the ethanol ratio). I've seen reports of mpg as low as 38 mpg in California and up to 58 mpg in Florida. With such high mpg vehicles as the Prius, the mpg numbers dramatically change with seemingly insignificant changes to the fuel mixture.

Generally, the mileage per gallon reports in California are highest during the summer months and lowest during the winter.

Mack

As spring arrives (say, during March), I shall watch my MPG with interest. I still haven't found out whether the UK fuel market varies its mixes seasonally. It seems plausible, though.

I've seen this mentioned before...odd...because I know that the recip engines on a large bomber that I used to fly would develop more power during colder weather than warmer.

They had limits on the maximum torque and manifold pressure that you could apply on takeoff and during very cold temps you'd reach limiting torque before manifold pressure.

When it was warm the manifold limits would be reached first.

Therefore one would think that the engine would be more efficient in cold weather and would give you better milage.

At a given atmospheric pressure, i.e., mean sea level, an engine will work more efficiently in cold air than in hot air because the cold air is denser. Offsetting the increased efficiently is an increased warm-up time in cold weather. Not only is the engine running on a richer air/fuel misture longer, the automatic transmissions delay shifting into overdrive before the coolant reaches a certain temperature. There are also differences in winter and summer fuel blends.

"Ray O" wrote: snip

Yes, that makes sense, so I guess if you were to operate a car for many many hours at a time instead of short trips you may actually get better gas milage in cold weather than warm.

With the same fuel, you should get better fuel mileage in the winter than in the summer.

My friend with a prius in the uk is fascinated with the 9kwh battery packs that are available in the states, these bring the equivalent mpg to 180mpg, for the first 50miles or so, providing you keep below 40mph. This would be ideal for him as he only commutes locally for 90 percent of his driving.

mrcheerful

Hey, maybe that explains the odd occurrence someone posted a while ago, where he filled up with Shell Premium and found noticeably better MPG as he drove his often-traveled route. My wild-ass guess is the Premium tank, with very low usage because of price, may have still held summer fuel. Just a thought - -

Chuck

Presumably that is a different configuration of Prius? Do those somehow charge that bigger battery off the domestic mains supply then run as a purely electric vehicle for a while? AFAIK, the standard (well, UK version) of Prius assumes a certain capacity of battery and maintains the charge entirely by use of the petrol engine and generator. I just don't know if UK mains power (with all the losses involved in charging/discharging) would be cheaper than doing it the "in car" way even with our petrol prices -- not having done the sums.

Sounds reasonable, or at least possible.

The last recip bombers we used as I recall were the reworked B26s in Vietnam. Before then it would have to have been the B36. Do recall a few KC97s during the mid 60s or Japan, though. Believe they were ANG birds, though.

Those battery packs were modifications by technically adept owners and are not factoy options.

I think a more likely explanation for the improvement in fuel consumption is that the vehicle's ECU advanced the timing because of the premium fuel's better resistance to knocking and pinging, resulting in better performance.

"TWW" wrote: snip

No, actually I was referring to the Argus which went out of service in 1981, replaced by the P-3 Aurora. The Argus had 4 Wright R-3350-EA1's. These were 18 cylinder, 3700 BHP turbo compound engines.

They are now mainstream, available to the public (apparently) including in the uk. There is an interface to the computer and you plug it in overnight. If you assume that you charge 9kwh plus losses, say 10 at 8 p a unit, then that is about 80pence for forty to 50 miles (and that is a worst case scenario assuming no braking !

see the uk distributors at:

The plug-in hybrid seems like a clever idea. It is not a factory conversion so I wonder what the additional cost will be.

Interesting idea and thanks for reporting it but I think I shall stick with the orthodox configuration for now. Reasons: I don't feel a need for the bigger battery (&c) at present; the new bits will not be free; it would soon become tedious to plug in when I park at home, leave cable running out of some house aperture (or from a socket installed in the house specially), unplug and stow cable when I use the car. Leaving it as long as possible allows the technology to mature more. Of course, time may change this.

I was not suggesting that it was imperative to get, merely interesting, also of course there is no requirement to recharge it every day, that would depend on your driving needs, it will still run as a normal hybrid.

I have just seen a ballpark figure of 11000 dollars for the conversion, that is about half the cost of a new prius in the states !!

mrcheerful