This improvement discovery is a truly amazing experience for me to share with y'all. Let me start by saying: Wow! It snowed here this morning. The temperature this evening was only 32°F. Time to block the grille. For the 2010, I decided the 3 lowest slots needed blocking. Then, I went for a drive... figuring it would help with heat retention while waiting stoplights. Little did I know what the Prius had in store for me. Blocking is far from necessary. When the coolant temperature finally dropped to 145°F, to my surprise, the engine stayed off. Whoa! The Iconic model always started at that threshold. The 2010 didn't, despite the heater temperature set to HI and the fan on the second slowest speed. So, I decided to seek out a testing area. There was a mile-long frontage road nearby: no traffic, 30 MPH limit, non-stop loop at the end, starting with a coolant temperature of only 148°F. It was an ideal set of conditions. I drove 1.3 miles on it in stealth (engine at 0 RPM) before the engine finally fired up for heat. And to my surprise, it quickly shut off again, automatically resuming my stealth drive. I couldn't believe what I had just witnessed. The new threshold appears to be 114°F. The reveal in Detroit at the start of the year hinted at impressive improvements for us to discover later, but this one really blew me away. Prius driving in Minnesota sure is going to be exciting for me this winter. Hooray! .
Oh oh, I hope this doesn't mean we're going to freeze inside the car during stop-and-go traffic when it gets really cold outside during January/February. I imagine that it could take a verrry long time to warm up the car at engine temperatures of only 114°F...
I see that you've finally got the snow that we got on Thurs. Yeah I am impressed with the cold weather performance. I was surprised that my 12km route was enough to have the engine shut off halfway through after sitting outside for the entire day. In the Gen II, the 15km route would've taken nearly all of that 15km before the engine would shut off.... when stopped. This one shuts off while in motion (sorry, I forgot the stage)
Nope, no concern about that. We'll stay warm. Problem was that the Iconic model was being overly conservative, starting the engine back up even though there was heat for the cabin still available. The reason was for the emission system warming, which isn't necessary anymore. Design changes allow the engine to stay off longer. The result is higher MPG. Gotta love it! .
John, the weather for us in Iowa has got to the ridiculous stage as we are setting record lows(for this date). My wife commented today that the heater on our new Prius is increditable as she is always cold when the weather gets below freezing, but she said it will "cook you"in short order. We also noticed that the engine was not running any more than usual to keep the cabin warm. Quite an improvement from our GenII.
Just as I thought. Easter egg is not in ideal condition but in the extreme weather. I am curious to know the Insight owner experience too.
Oh and to add to this, ECO mode does affect heater output. I can hear the fans speed up/slow down as I toggle ECO mode.
That hidden extra boost in efficiency has not been found in the summer/spring temps (just a typical ~10% increase as EPA MPG indicated). I knew the unexpected boost would be in the winter after reading about the Exhaust Heat Recovery for RX450h. Prius shares the same Lexus next-gen EHR tech which is more refined than the iconic model's thermo bottle system. The Insight may be able to hang MPG close to the Prius (it should exceed due to it being a smaller and lighter car) in ideal temp conditions. As the temp drop, I expect the Insight MPG to drop much more than the Prius. Stop-N-Go traffic in the winter for the Insight will not be a pleasant drive. Prius is much more refined to handle such condition with heat in the cabin. Ford hybrids (Fusion and Escape) do not have any heat recovery system so I expect their MPG to drop dramatically in the winter as well. Recovering braking energy is the last-gen hybrid tech. Unfortunately, Ford hybrids do not have the latest hybrid tech that recover heat for the cabin as well as the gas engine (to shut down more often). I am pasteing the "Calling All BTU" section from RX450h EHR info:
Interesting read. Good thing it doesn't freeze here for Prius drivers, but it still can get chilly 30-40 some winter mornings.
I got to confirm the 114°F under real-world conditions today. About 10 minutes into my commute home, I simply pulled over and parked. Sitting there with the heater set to the fan-speed set at medium, and the system in ECO mode, I waited patiently. Sure enough, the engine stayed off until the coolant finally dropped to 114°F. I didn't pay attention to timing of how long that took or how long the engine ran. The thought hadn't occurred to me. Because at 39°F outside, it was quite warm by Minnesota standards. What I did observe was the shut off threshold. That appears to be 128°F. The engine RPM dropped significant then; however, the gauge revealed 130°F by the time the engine had stopped entirely. Not having the engine start back up at 145°F anymore sure is a nice improvement. .
Nice discovery, John. Thanks for sharing it. Will you modify your grill blocking just because of this finding?
I already did adjust the blocking, under the hypothesis that we'd discover something like this. That contributes to the reason that timing hasn't been a focus. Obviously, heat will last longer with less radiator exposure to the elements. At what temperature was my question. Knowing precisely when the engine would fire back up while waiting for a stoplight was intriguing with the Iconic model. It made me wonder what an upgrade could bring. Now, I know. .
