I get terrific mpg, but I sure don't understand it.

I guess my suggestion is don't get too worked up about gas mileage on specific trips. I pay attention to it, but basically what I care about is what my entire tank average happens to become.

And yes, if you are on full EV..your MPG should be maxed...because basically the vehicle isn't using gasoline at all. But if the vehicle is cold and/or the battery charge is low, the vehicle won't stay in EV mode.

My Prius never starts out in the morning remaining in EV very long. When I first start it, it will EV while I back up, but the engine pretty quickly kicks in, even at low speed, because The Prius wants to warm up the engine, and/or charge the battery.

But I don't know how the condition could exist where you say you are in full EV operation, but are only getting 1 mpg.

 

So the EV drive lamp is indicating the the engine isn't propelling the vehicle but I bet it's running to warm up at that stage--thus your mileage reading.

As for the differences between the earlier trips, it's likely that the 85+ mpg trip accomplished that with a net decrease in battery charge which got made up in the next trip.

It's not magic but it can be startling until you get used to it.

 

Sure, and using the battery makes the gas mileage higher. This isn't an electric vehicle. Everything has to come from the engine burning gas, in the long run.

When you're charging the battery, most of the energy gets stored but some gets lost to heat (since charging isn't 100% efficient).

When the car is assisting the gasoline engine with the electric motor it's converting some of the battery charge to work done by the motor, but some gets lost again (since the electric motor isn't 100% efficient).

EV mode is worthwhile in situations where the engine wouldn't be efficiently used (slow subdivision streets, parking lots, stop and go traffic) and the car will use it in these cases more or less automatically.
If you force EV mode (by using the EV button) longer than the car would use it by default, you're forcing it to drain the main battery somewhat. That's more work the engine will have to do later on to bring the battery back to where it was.

You know what I use the EV button for? Moving the car in and out of the garage without the engine starting. I can only do this in the warmer seasons because below a certain temperature the car won't even allow that.

There's a lot of information searchable on this site (most of it for the main hatchback Prius, but still applicable to your car). Specifically visit stickies about the stages that the car must go through during warmup.

Have fun!

 

Might not help, but, the first 5 miles warm up the car, if the hybrid battery was full and helps propel, great, but then it's depleted and needs a recharge, anyway, so after 5 miles the mileage should be excellent, then trip 3, the hybrid battery is depleted, the ice must propel the car and charge the hybrid, so the mileage goes down, it's still better than a poke in the eye

Simply driving the speed limit is all it takes,btw

 

Yap, forcing EV gives short term gains and poor long term average.

 

How much elevation change did each trip have?

 

^^^
Google Earth can give you an elevation profile of a route between 2 points! | PriusChat

 

If you haven't already, consider enrolling with Fuelly.com.
Due to the state of charge and altitude fluctuations your best indicator is calculated mileage over several fill-ups.

 

I commute 20 miles each way. My employer is 300 ft lower than home. I generally get about 10% - 15% better mileage going to work than coming home.

 

Trip 3 it is likely your battery was already drained before you shut off the A/C (from both A/C use, and the small amount of power used off the battery when gliding). The engine probably had to turn on for a while to recharge. If you were truly gliding (i.e., being in EV but not using battery power in EV), keep doing that. It will give you the best mpg overall. Where you get into trouble and start getting inefficient is when you use the EV to propel the car (in other words, it's simply shutting the engine off while still gaining distance that gets the Prius awesome in-town mpg- it's using the battery that creates inefficiency). Try giving the car a little bit of extra recharge when gliding, too.

In your "Second situation," even when your foot is not on the gas pedal the engine is running if you just started the car and the engine is cold. You're not in EV and you're still using gas because the engine is warming up. It also takes inordinate power to get up to speed before gaining distance. This will make your mpg low until your engine warms up and/or you get up to speed for a good while.

 

If the ICE is warming up then the EV indicator will not be on, even if the car is using purely electric for propulsion. It might sound odd to have the ICE running while using EV for propulsion, but that's exactly what the car does sometimes during the warm up cycle (low battery charge or high power demand will switch propulsion over to the ICE).

As mentioned there is a huge variable from trip to trip in given mileage, very often this is related to the battery charge. A trip where the battery gains a lot of charge will usually show poor mileage while a trip that nets a large loss in battery charge will show as high mileage. In the end any usage from the battery will eventually have to be replaced by burning gas, so it's better to determine over the course of several trips, or one whole gas tank at a time.

These cars do take some mileage on them to level out, mileage should increase over the course of your first couple of months. In other words, they need broken in, which takes maybe 2000 miles.

 

Same here. If you could shift the transmission into Neutral with engine off I wouldn't even use it for that (and yes, EV's often locked out, depending on the phase of moon as much as anything...).

With previous cars and our slight downhill slope out of the garage, I'd just shift into Neutral and use Flintstone Mode.

 

If the EV indicator is on, the ICE is OFF

 

But sometimes you are using full EV for propulsion and the ICE is warming up. The light won't be on in these instances.