Starting HV mode at 60 MPH

can't be sure, but i wouldn't do it. i'm sure toyota takes precautions, but i would warm it up before entering the highway. they don't exactly have a pristine record of protecting their engines.

 

I don't have a prime, so I can't be sure, but I'm guessing that the car runs off the traction battery while the engine warms up. It most likely keeps a reserve for this reason. If true, it wouldn't hurt it to start it at any speed that the EV motors and battery can handle without the engine.

 

once the engine is producing enough heat, most likely.

 

I would suspect that the warming up engine charges the battery while idling to warm up with the battery driving. It probably doesn't switch over to engine provided heat though right away because the engine temp isn't high enough to provide it.

 

We've seen how PHV (2012-2015) protects the engine, allowing highway-speed start-ups while reducing the burden by heavily favoring electricity until warm-up is complete. We have seen similar behavior with Prime now too. There is nothing else to doubt anymore. We are sure.

 

when i turn on the heat, in ev mode, the engine comes on. when i step on the accelerator, the engine revs. does this behavior persist in prime?

 

I do this all the time.

From a cold start, my Prime is in EV on surface streets and until I get up to speed on the freeway (i.e. 65+ MPH). Then I switch the car into HV mode and the ICE runs thru it's startup routine. While the ICE is going through warm up (about 3-5 minutes, not sure), the car is running off of the traction battery and the ICE is providing very little energy (if any) to the motors. This keeps the ICE from being stressed from a sudden cold start. Keep an eye on the energy diagram on the 11.6" screen and you'll see the engine icon go yellow when it has finished it's warm up period.

You can see the traction battery level drop down while the engine is in warm up mode - you'll get the lost charge back eventually after the engine warms up and "tops you off" so to speak.

Also - keep in mind that since the engine has 0-20W oil, it can warm up and lubricate quickly. That's what it was designed for.

All of the above is based on EV Auto being off.