engine performance question

The engine/battery operation is normal. The control computers protect the battery state of charge and engine temperature automatically. Don't be alarmed.

As for City mileage, this chart may help you understand what you need to do:

This chart assumes a warmed car that usually takes 15-20 minutes. To achieve the old EPA numbers, you need to drive at speeds that sustain that MPG. Your NHW20 can go a little faster but not a whole lot.

Also, you need to avoid passing through 42 mph, a boundary between two control modes:

• 0-41 mph - allows engine off, battery operation if there is enough charge and the speed and terrain driving load is low enough
• 42-105 mph - the engine must always turn

Transitions through 42 mph leads to switching between control laws and can lead to extra fuel being burned and the overhead of starting and stopping the engine. My rule is to use 0-38 mph and 46-65 mph for my driving. This gives me a solid 52+ MPG and much more during warm weather.

GOOD LUCK!
Bob Wilson

 

Everything that you state is normal behavior from a Prius. Don't worry! You will be very lucky to achieve 55-60mpg in your Prius. The new EPA numbers on the Prius are around 48-50 mpg and that is what you state you are achieving.

I also have an 05 Prius (with 117k miles now). When you start the Prius up, it may stay on battery for a bit, but it will definitely kick into the gas engine not long after start up. The first 5 minutes will give you the worst mileage since the engine will need to heat up.

Depending on your driving style and the terrain, the battery might stay on from a stop or the gas engine may start up to "assist" with power. This is the beauty of the Prius. Don't be alarmed....it is all normal.

I have had my Prius stay on battery up to 50 mph when I start on a downhill grade and go very lightly on the gas pedal. At other times, I've had the gas engine kick on immediately to provide power on an uphill start.

Over the next few weeks, you will learn the nuances of your car and how to drive it to stay on battery power for as long as you can. Congratulations on your Prius and welcome to Prius Chat!! Ihope you find this information helpful.

 

Yep.

Your mileage will improve as you learn to drive the car.

Also, as Bob indicates above, there are certain speed regions which lead to better mpg. I have found that I get the best mpg in the 45 - 50 mph range. Your mileage may vary.

 

The ICE will come on at 42 mph unless you happen to be coasting down a hill at 41 mph or less with the ICE off, flick it into neutral, and then coast over 42 mph in which case the ICE will stay off. Just because the graph is pegged at 100 mpg does not mean the ICE is not running. Depending on coasting speed it can get up to 240 mpg with the ICE still idling.

PA P

 

Wow. Nothing like throwing a whole lot of technical information at a newbie!

I think what might help brooksq more is:
1) The engine needs to stay warm for best operation and low emissions, this means it turns on when it cools off, or if the battery gets too low and needs to be recharged, as well as when you need engine power for driving.
2) City driving is good because of the low speeds, but not with all the stops and starts. Highway driving will drop the faster you go, particularly above 65 mph. So it depends on your particular driving environment and driving style. It's not measured, but 'suburban' driving is probably the best style - often low speed, but fewer stop lights, and more relaxed start/stop requirements before people honk at you.

Basic ideas for better mileage: Make sure your tires are at recommended pressure or above (many people go 40 psi in front, 38 psi in back), slow down in advance of any stop, don't try to use the battery only when accelerating - think of the battery as an emergency boost, it's actually more efficient to use the engine only when accelerating (watch the arrows on the energy screen).

hope this helps

 

Please understand the Prius warming up stages.
http://priuschat.com/forums/knowled...perating-mode-availability-reference-aid.html

Ken@Japan