Do You Get Better Fuel Economy Just After a Rain? (and the weather is moderate)

61.5mpg lifetime - 82mpg in recent months

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"fanatic" is what the lazy call the dedicated

No. The water on the road increases the rolling resistance, and kills my Insight's MPG!

troy

Got to be careful wording polling questions - meant just after a good rain and the roads are relatively dry and the temperature is between 50F and 80F.

My experience is my FE seems to get a little better in those situations.

During World War II, bombers used water injection to increase range. For years, water injection was used as an after market enhancement when most cars used carburators. Even though most vehicles use fuel injectors, my after a rain experience makes it seem like water injection could still be useful. Realize I don't have proof.

61.5mpg lifetime - 82mpg in recent months

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"fanatic" is what the lazy call the dedicated

I believe water injection was to reduce knocking. I don't think it would be needed on todays cars. Though I think some ricers use it with nox or turbo or whatever.

My hydroponics experiment

You ever notice how hard it is to lip read cartoon characters?
"Crazy is what the sane call Delta Flyer"

Probably two reasons for this:
- still partly cloudy, so your A/C runs less

- the 50-80 F range is a "sweet spot" for my insight. It likes that temperature, and gets the best fuel economy.

troy

As far as I can recall, I'm not using the A/C at all either on the day after a rain or a fair weather spring day that it has not rained all week long.

My suspicion is humidity is a factor.

61.5mpg lifetime - 82mpg in recent months

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"fanatic" is what the lazy call the dedicated

My best MPGs were in Utah, where it's as dry as a bleached bone. I routinely scored 105-110 mpg during daytime sightseeing trips..... with my personal best record at 123! ( went to see the famous golden spike... there was a tail-wind pushing me down the road)


Since I came back to the humid east-coast, my MPG plummeted to only 90-95 mpg on the interstate.

troy

Altitude may have been a factor.

Last month I was going 75mph (the speed limit) on I25 from Denver to Fort Collins. My mpg was around 70mpg. The altitude was about 5,500 there. I can't get that kind of fuel economy at 75mph in Texas near sea level.

61.5mpg lifetime - 82mpg in recent months

Best Run >
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"fanatic" is what the lazy call the dedicated

I read about an experimental rotary engine that used hydrogen as a fuel, but only minimally to vaporize water, and the steam actually caused the motion. The theory was that the expanding gasses of the burning hydrogen would be a lot less powerful than the expanding water vapor that expands in a much larger ratio than the burning hydrogen. It makes some sense that a little water could improve power output, but it may be tricky to offset the cooling effect the steam has in it's formation using gasoline. Perhaps in combination with a lean-burn mode it would help reduce the excess temperature caused by the oxygen-rich mixture, although it may well prevent proper combustion. There may be some merit to using water/steam enhancement, but I think the engine would have to be designed for that in the first place to truly benefit from it in a substantial way. It would be interesting to see if there's a difference in emissions during the post-rain driving conditions.

2001 Prius Photos       2005 Prius Photos
'97 Prius Simulation Prius inner workings

Yep --- humidity is a minor factor in MPG, high altitude makes a major difference, particularly at highway speeds.

R2-E2, 2G Prius.
Highway/City/Husband/Wife MPG: 56.5, as of 12/2005, 26K miles

Jac Nasser, Ford President: "We are planning to launch a hybrid version of
this car [P2000] within this year [1998]. We will also make FCEV available in
2004."