Cold weather and MPG

jamesearthdrum said:

Hello,
I'm new here and have found the reading interesting. I bought my 2002 Prius in December and have not managed to get more than an average 38 miles per gallon. I am at about 3200 miles now, well past the recommended break in period. Is the cold weather in New England a possible cause for the lower than I read here mileages? It has been consitstantly below freezing since I bought the car. I've started running with the defroster off and the fan set at AUTO. My commute is about 40 min. each way mostly secondary roads with speeds under 45mph. I've installed the remote cruise control available from Costal Tech. and use it to keep my speeds constant at around 33 - 35 mph whenever possible. An eye on the energy screen show the gas motor kicking in very quickly when lleaving a full stop, normally before 10mph. Any suggestions on what I can do to begin increasing my mileage? Thanks

james

Click to expand...

all cars have lowered MPG in the winter, only the Prius tells you how bad it can be...
(anything from not-clear roads (slippery traction and pushing slush out of the way), extra weight of snow on the vehicle (also increases aerodynamic drag), cold air is denser which is more difficult to push out of the way, cold air affecting combustion (air/gas) ratios, lower tire pressure from colder tires (tire air pressure changes linearly 1psi per 10^F change), and winter reformulated gasoline, can all take their toll on a car's MPG.
Another big MPG killer on cars in the winter is the bad habit of starting the car and letting it idle to "pre-warm" it up...

For Prius-specific ideas for better winter MPG - garage your car if you can, if it's REALLY cold where you are consider an engine block heater. Otherwise, wait for the warmer weather to arrive in the later spring. Don't forget to check that tire pressure - MINIMUM of 35psi front / 33psi rear, when the tires are measured cold (not been driven upon).

(The Prius is foremost a low-emissions (SULEV) car, with high MPG as a nice side-benefit. Emissions components have to be warmed up to proper operating temperatures when you first start your car (takes 5-10min, maybe longer depending on outside temp, to get that blue cold coolant light to go out), so your engine will run to warm things up. The hybrid battery likes to be around room temp, just like people, so it sucks air from the cabin for heat, since you'd probably have heat on in the cabin to stay warm (engine runs to provide heat). So, expect less "stealth" time in the cold winter months. You've already taken care of the defroster setting (front windshield selector) that may cause the engine to run to run the AC pump to dehumidify the air...

anyhow, things will get better once the warmer weather comes around.
-Michelle, owner of a 2001 Prius (delivery 2/2/2001), now in it's 3rd winter in the suburbs of Boston, MA... MPG and other data (pretty graph on the "raw data" link) at http://www.kluge.net/~felicity/prius.php

First of all, congratulations on your purchase of the Prius!

I took delivery of my 2002 Prius on 4/4/02 and through the end of '02 averaged 46+mpg combined highway/city, with highway mileage better than city (contrary to Toyota's claim). Since the beginning of '03 and with our severe n.e. winter I've been averaging c. 38mpg. It was lower, around 35 mpg mostly in the city, until a recent 700-mile road trip raised it to 38. So I'd say that your reported mileage is about right, based on my experience. I also have cruise control (factory installed) and always run the fan on auto, avoiding the AC defrost mode unless absolutely necessary.

I'm keeping careful records on gas purchases and mileage in order to comply with the reporting requirements of the $1,500 grant from the Commonwealth of Pennsylvania's Alternative Fuels Incentive Grant Program. That, plus the $2,000 clean-fuel adjustment to income on IRS Form 1040, makes me an especially happy Prius owner. This is the best car of the seven I've owned, and I am just waiting for a hybrid mid-size SUV-type vehicle, hopefully from Toyota, to replace my '91 Explorer.