Frustrated prius believer question

Yep, you should. You see, if you don't, you'll be wastefully speeding up and slowing down as you approach pedestrians you didn't see until you were almost on top of them. (Assuming cold dark mornings) We all know the first twenty minutes are not fuel efficient. Let's say your ride to work last 20 minutes. If you let your car warm up 5 minutes that means the last 5 minutes are fuel efficient (5 plus 20% total operating time). So, the last five minutes makes up for the first 5 minutes. Theoretically, you could let your car warm up 20 minutes which would make your whole trip to work fuel efficient. Can't argue with that. But I'm sure somebody will. mark_

Greetings from Flagstaff, Arizona! We make a lot of trips to the Phoenix area (about 1200 ft) and I agree the economy is a little better there - probably about 5 mpg - but Phoenix is mostly flat while our mountain town is pretty hilly.

Come to think of it, freeway mileage is noticeably better at lower altitudes. Hmm....

Mike

Greetings from Rome, Italy: I also noticed an higher fuel comsumption during winter with my Sept.

2005 Prius, but no difference from Rome to Torino (about 450 miles). Are you sure about the quality of the fuel? Usually fuels sold in different areas, also if the same brand, may come from different petrol, may be that this is the problem: why not try to refuel from another brand?

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That's another possibility. We may have a different formulation at high altitude to prevent vapor lock. There aren't that many carbureted cars running in the US, but there are enough that without controlling vapor pressure the streets would be blocked with dead vehicles.

Mike

Things like tail winds and following close behind another vehicle can have a positve effect. I say most of what we experience is out of our hands though. We may think the driving conditions in other locations are similiar but all it takes is an accumilation of a minute here and a minute there of a bad variable over and over; not enough to remember it but enough to effect mileage. This summer I reset the fuel efficiency gauge to zero and drove 30 miles west on the MA turnpike at 55 mph. Heading back east on the Pike I kept it at 62 mph. When I reached the toll booth the gauge read 66.9 mpg. I did the same thing recently, not changing my behavior at all and the gauge read 50.5 mpg. In either case, by the time I got home it read 52.5 mpg. Traffic congestion off the Pike worked for me and against me. My fuel efficiency (on paper) for 10,000 miles is 49.9 mpg for 2004 and 50.2 mpg this year. We didn't go to Colorado :(

note that tire pressures will drop 1psi for each 10^F drop in outside temperature... so if it was a hot summer day when you last checked your tire pressures, and it is a chilly winter day now, your pressures are likely down.

Well, assuming that the length of trip and type of terrain hasn't changed, and that the type of fuel hasn't changed (many areas are now using E10 or a winter blend, and some gas stations offer higher-octane fuel than others for the same advertised grade), there's always the question about the interior temperature settings and front windshield defroster use... Heater is run off of "waste" heat from the gasoline engine (and yes, the engine will run just to provide you with more heat). The front defroster uses the AC compressor to dehumidify the air blown at the windshield, and that AC use gets its power from somewhere (and doesn't light the AC light to tell you the AC is being used)... On a NHW11 Prius the AC is belt-run off of the gasoline engine, causing the engine to run more often. On a NHW20 Prius the AC is electrically-driven off of the hybrid battery, but then the engine may come on to recharge the battery...