"EV mode unavailable" flag

Either that, or drive around in reverse, which is all electric.

 

Is it really? That's interesting. Would the ICE come on to provide charge for that if you went a long way in reverse? I ask because I once had to drive backwards for upwards of a mile on a highway due to an accident.

 

The ICE still comes on when in reverse. When I intend to just back my cold car out of the garage without lighting up the ICE, I have to be fairly quick to get it out and turn it off before the ~10 second grace period expires. Once out, even shifting to Park isn't enough to keep the ICE off, I have to shut the ignition completely off.

 

Yes, reverse is all electric, the ICE will still come on, and it can provide power if needed; the ICE spins, and MG1 spins backwards to counter its forward motion, generating electricity which can be sent to MG2 spinning in reverse, or to the battery.

The reason is that there are no gears to shift; in a normal transmission, reverse is accomplished by adding an extra gear to reverse the direction of rotation from the engine's output. In the Prius, the ICE is permanently connected to the planetary gears, which are all permanently meshed together (there's no clutch or shifting mechanism). Since you can't run an engine in reverse, the HSD takes care of it by using the electric motors, while still allowing the engine to run in its usual forward direction.

That said, I'd think that for backing up for a mile, it would be easier to do a Y-turn and not get a crick in your neck...

 

I would have preferred to turn around, of course, but there were hundreds of other cars backed up behind this accident, so it was not an option. Everyone was driving in reverse.

 

It is a shame that I can't use EV to back out of the garage for a wash, for about 3 months a year. This is about the only useful purpose of EV mode. Now I have to wait 90 seconds for the ICE to warm up before shutting it off or the ICE will run rough on the next start up.