Bought my 2nd Prius/cty mileage

For the first 1.5 miles, both our 2003 and 2010 Prius achieve the same MPG. But once past the warm-up, the 2010 Prius MPG rapidly improves so by the end of my 10 mile commute, they are all but equal. But if I add an additional 5 miles, the 2010 greatly exceeds the 2003 Prius as in this driving stunt:


As for a technical reason, let me suggest:

• 2004-09 - has a thermos of hot coolant from the last trip. This shortens the warm-up time faster than the coolant heater exchange in the 2010-current. MITIGATION: get a block heater installed to warm the engine block saving an additional 1-2 minutes of warm-up.

There are other, warm-up techniques that can improve 'cold-start' performance:

• First 1 to 1.5 mile - use 25 mph route with maximum use of "N" to coast. This minimizes the fuel burn while the engine warms up. Sometimes this is nothing more than using a neighborhood route instead of a cross-town street.
• Coolant < 40C - the engine will not shutoff.
• Coolant > 40C to 55C - the engine will only shutoff when stopped. Turn off heater when stopped so engine will stop. Turn heater on when pulling out or driving.
• Coolant > 55C - drive normally but try to take routes of 40 mph or less so the hybrid mode saves maximum fuel.
• Lubricants, tire pressure - engine oil, transaxle oil, and maximum sidewall pressure in tires. During cold weather, tire pressure goes down so it needs more frequent attention.
• Check 12V battery - with the car off, make sure it measures above 11.9V as they do not last forever. A Prius with a failing, 12V battery cell will still run but suffer a mileage hit as the car wastes energy trying to charge it.
• Fender, air-inlet block - reduces air drag, especially with dense, cold winter air, and help engine warm-up.

As for the traction battery charge, let the car handle it and don't worry.

GOOD LUCK!
Bob Wilson

 

Has your 2011 had the e0e recall applied? It might actually help the city mileage.