2007 Prius Mileage not good 39ish

Welcome to the forum. :welcome:

Winter temps are really hard on Prii. They're also not good on other vehicles, but it's more obvious on the Prius because of all the gizmos for tracking mileage.

Suggestions/info:
1. Short trips are mileage killers. If making multiple stops on a trip, try to go to the most distant point first and work your way back. This allows the engine warm-up time.
2. Install an engine block heater (EBH). This reduces warm-up time when you start your trip/commute.
3. Install a grill block. Allows the engine to stay warmer in cold weather.
4. Remember that even at 39 mph, you're still doing better than almost any other vehicle in your area.

 

What MJFrog said.

What is your driving like? Lots of short trips? Short trips + cold weather = BUTCHERED fuel economy.

Check your tire pressure, make sure it's good. Winter gas SUCKS and will reduce economy. Check into a grille block, or use foam pipe insulation. Search on the subject and you'll find different examples.

It's just a fact of life that you will get lower fuel economy in the winter. Your habits or conditions can magnify the reduction as well.

 

Same thing happened to me on the last 2 tanks. usually 47-48, but 39-40 on last 2. Current tank is @ 44. Drove to NYC on last tank and got 50.6 on hwy. All seems to be ok now. I drop to about 44-45 in the winter. You are probably ok, but watch your mileage as the temperature fluctuates and see waht happens

 

news flash: all cars get lower mileage in the winter.

Winter gas has less energy
cold air is harder to move through
heater robs heat from engine - forcing it to STAY ON to provide heat.

 

My 2007 according to the trip computer,gets over 45MPG on the highway,but much less on short trips.Maybe even less than 30MPG.I'm convinced it's because the engine does not have a chance to warm up and the engine keeps running when the car stops.

 

Yep on the last points. However, if you turn the fan on your HVAC system to OFF while stopped or at low speeds, that will prevent the ICE (internal combustion engine) from running to provide cabin heat.

Once the ICE/coolant is warm enough, the ICE doesn't need to run to provide cabin heat. On the 2nd gen, the cutoff is coolant temp of 145 F. If coolant temp (FWT on ScanGauge for Fahrenheit Water Temp), is <=145 F, having the heat on w/the fan on should cause ICE to turn on.

So, don't turn fan on w/heat unless you're in a condition that would require the ICE to run anyway such as hard acceleration or speeds >=42 mph.

Those in cold weather should consider blocking the grille. It's a cheap way to help reduce heat loss during initial warm up. An engine block heater will help too, but that's much costlier.