I have done this a couple of times. Not that hard to do, just vary your speed during the drive home. On freeways, I even used the cruise control a bit, but I constantly varied the set speed. Sometimes I did not even have to do that, as the car in front of me did that for me (since it is a radar limited cruise control).
The advice about varying vehicle speed during break in pertained to geared transmissions in which different vehicle speeds were needed for different engine speeds. In a Prius, the engine speed will vary even if the vehicle speed is constant.
Yes, you are correct and I am aware of that. But it still can't hurt to vary the load on the car in this break-in period. Or, so one would think.
Drive it home a route that's a little less direct, varied conditions. With a brand-new car, where you not that familar with the controls, that's maybe safer anyway, compared to high-speed, no-stopping freeway.
I bought mine almost 800 miles away from my home because I wanted the base model PHEV. Toyota in their wisdom distributes all PHEVs according to how they feel the market will support. Apparently in Florida that doesn't mean base model vehicle (well OK, 1 in the wrong color). In the East, it appears there a distributions of them closer to DC and then tons in New York/New Jersey. I didn't feel comfortable launching the ICE hard core down the interstate for 10 or 12 hours when the car only had 18 miles on it. I paid to have it closed transported to me. That was extra cash but it still came in under what Southeast Toyota (SET) dealers seemed to want to mess with. I even avoided the stupid "paint protectant", $600 for 4 oil changes, and all the other silly crap (SET) adds on "at the port". You could always transport it yourself if the deal is worth the hassle.
About the speed, they just have the vague directive to avoid very high speeds or something like that.
Just a data point here for my 2025 Camry XLE. Although the manual sats engine breakin is 600 miles, I did not really see economy improvements until over 1300 miles. Perhaps the ECUS need that time to adjust to the behavior of your particular mix of components.
