Prius -- 23 mpg??

I'm in the northwest suburbs of Chicago, and today's temperatures in the teens seemed very pleasant compared to the last week!

Try setting the interior heat temperature a little lower and see if the fuel mileage improves.

As I have posted here previously, my Prius (2005 UK "T4" version) is sensitive to factors like the petrol engine having to warm up, tyre pressure, car's general state, fuel and driving habits. For comparison my typical figures on clear roads are: summer 45mpgUS; winter doing short journies (30 mi, 3 hour midway pause) 42mpgUS. Recently I found my tyre pressures were roughly 10% low. Putting that right boosted mpg by 1.6mpgUS -- rolling resistance matters, especially in the Prius, whose standard tyres Toyota make a point of saying are meant to cut energy loss. If you've been ploughing through snow/slush, I'd not be too surprised by lousy mpg, though your figures do sound low. As Ray suggests AFAICT, have you kept it standing around in extreme cold, with electrical loads on full and heater running?

My 2005's present tankful in a suburban, 10-degree setting is showing in the low 30's. I have found that I can boost the MPG by simply using the B transmission range when slowing to a stop. I tap the brake to alert the following driver I'm slowing (why on earth didn't Toyota trip the brake light in the B range?), then I shift to B and let the generators slow the car.

I'm a big user of the B range. I credit that with raising the MPG over what I see reported here. My best in the 11K miles on the car so far was 64MPG average in a hilly, 55MPH, summertme run in upstate NY. I go into B at the moment the downslope looks almost constant ahead -- usually shortly beyond the crest -- and shift back into D when the MPH has fallen back to 2 or 3 above the limit -- usually as the slope is flattening out. By returning to D while still coasting, I give the cruise-control time to adjust to prevent its hunting.

Cruise-control does a much better job of conserving fuel than my instincts do. I rely on it whenever I'm not in traffic or in an urban setting.

It does so by about 15MPG for me

If I notice a drop below my expectations, I look first to my driving habits. This is my first hybrid, and I find its requirements non-intuitive after a half-century of conventional cars.

I think the key lies in understanding that the Prius doesn't *give* economy; it *permits* it. The driver is a major part of the system.

Thanks for the suggestions (from you are others). Yes, tires certainly do matter. They were just fine, but I should probably check them again given how much colder it is now.

No slush. It's been cold for a while and roads are dry.

It's cold, so the heater is running but the temp is set to 67F or so. It doesn't seem to want to be set below 65F. Lights on when needed (not much choice there); defrosters are on a lot since the car is not garaged inside and they probably use a lot. I'm not surprised my mileage is lower -- just that it's so much lower.

Bob

Then Toyota did a bad job with their software.

There's no excuse for the car's driving requirements to be any different than any other car that's ever been on the road.

Let me guess: you're one of those idiots who drives along playing his dashboard video game instead of actually driving and paying attention to traffic and the outside world.

He doesn't sound it.

Say, Elmo, have you had a chance to use that Prius you said your employers(?) were going to lend you? Any impressions yet?

That is pretty pathetic mileage. My wife's Honda Accord hybrid with a V6 and zero to 60 of about 7 seconds does 25 mpg mixed driving no matter what the weather. Not very impressive but it basically is designed to give V8 performance with 4 cylinder mileage. That 25 mpg is with just about zero highway driving. Mostly stop and go crawling to work. Autoclimate control always on and she uses seat heater in the winter constantly.

In NJ here where is it in the teens during driving time we still get 45-49 MPG. Tomes

I'm not surprised. If the engine has to run to produce heat the hybrid function is less effective. For the hybrid function to be most effective the engine must be off as much as possible.

Still, that's insanely low. HE should have it looked at.

Tempted to agree - i get that from a heavily tuned 2litre turbo doing general driving during mid winter!

What is your driving mix? Twenties is common for short trips lasting 5-8 minutes or less. Have you checked tire pressure? My mom lives in upstate NY, takes a lot of short trips, and gets

Amazing! In typewriter font, all Andrew's lines are right-justified.

Interesting... I do this too, against the advice of a FAQ on Priuschat, which appears to be the best web-based forum for Prius owners.

Seems like the B is just like putting on the brakes, but doesn't wear the brake pads. Hopefully not the engine either. I experimented with going down the same hill twice, and the battery recharged much faster with B than merely by coasting.

I also use N a lot. Being used to manual transmission, I guess my hand gets nervous and wants to do womethign. But it does seems to save a lot of fuel just coasting when B is too much. The famous "glide" condition where there are no arrows on the Energy screen is duplicated by N.

A Usenet hobby of mine. A lot easier to do than it seems. And adjusting the wording is a good exercise in Use of English. :-)

I do this glide condition (no arrows) by resting my foot on the gas pedal just a little bit. Usually what I try for is to have it use the electric only with just a little more foot. I seem to be a net generator of electricity and want to use more than it normally uses.

I don't think that B affects the engine at all. It does not turn it on and does not light up any arrows to the engine. I just use it to slow down when I want to slow faster than a coast. (I too have a 'manual shift' right hand wanting to do something....) Tomes

Tomes

Another thing to consider is the reduced output of the hybrid's battery in very cold weather.

That seems awfully low. We have a Scion with pretty much the same engine and a conventional drivetrain and we get a consistent 29MPG with far worse aerodynamics. If I were getting 23MPG after spending the bucks for a Prius I would be rattling Toyota's cage.

A word of advice about the typical "service people" at the dealership: If their lips are moving, they are probably lying. "That's the way these hybrids are in the cold" is pure BS.

Did they service the car when you took it back? Like check the tire pressure, etc?

To a certain extent, yes. Once the car has been running a while, air drawn in from the seating area (through that grille at the RH end of the rear seat) should correct the battery temperature, for the rest of that journey at least.