A Question for Prius Drivers from the Frozen North.

My step-mother and father live in New Hampshire. She's been a Honda Accord fan for many years. She does a lot of highway driving, and always buys I-4 Accords with the manual transmission. Various factors have led her to consider changing to a new Prius for her next vehicle, purchase coming soon.

She has asked me a couple questions about the Prius, and I’m a tad embarrassed/flat-footed, since the questions relate to cold weather ops. I’ve driven my hybrids up north a couple times, but never during any challenging winter weather -- 99.99% of my experience is in mild-to-hot temps. They have a long (75-100 yds), smooth asphalt driveway that slopes fairly steeply up to the street. It's in a wooded area, so it doesn't get any solar heating. It’s a challenge to keep it free of both snow, and of more concern, ice.

The internet has led her to stories about the aggressively protective traction control that is, of necessity, an integral part of the Prius design. She’s worried that this aspect of the Prius might, in her case, prove to be a “show stopper” because of the allegedly poor hill-climbing capability under such conditions. Being stuck at the bottom is not an option for her. Unfortunately, I can’t credibly speak to how the Gen-4 Prius (actually, any Prius...) might actually perform under this circumstance.

Would any of our “north country” members care to comment?

 

I'm concerned about deactivating the TC/VSC, etc. (I've read the 2018 manual in this regard) for two reasons. First, their driveway is steep. With enough ice, it's hopeless until it gets a dose of sand or sand-salt mix. Under marginal conditions, without any TC assist, the climb would probably be impossible also. Notably, that video fails to distinguish the TWO "shut off" possibilities (press+release and press+hold the button). Of course, I'm not sure that keeping VSC while shutting off only TC would make any difference in this situation.

Second, if the TC is deactivated, is there still the possibility of over-speeding components in the transmission? This was, IIRC, a big issue in the Gen-2 car and was the very reason why the TC was so aggressive in the first place. With TC off, going uphill on ice patches, it would seem that there would be a pretty good chance of high speed wheel spin in the moments after losing traction. Still an issue with Gen-4?

 

Good point, I was wondering about that. There IS the switch in the Gen-4 car, which I remember being absent from the Gen-2. As for the manual, I've got both the print and the searchable pdf. I've already run the search, cover to cover in the 2018 manual. Despite the appearance of the TRAC/VSC OFF button in the Gen-4 car, in the section addressing getting one's self unstuck, this blurb appears,

Apart from the instructions on how to turn off TC only or TC & VSC together, this is the only morsel in the entire 820 pages that touch on the issue. I'm thinking you're probably right, but Toyota doesn't want to pin itself down, or encourage any wheelspinning, even if the car is better equipped to handle it. EDIT: Maybe it's time to revive my dormant TIS subscription. . .

 

I know both of them do snow tires each winter (each has a set mounted on steelies for their respective cars), but not sure whether or not they do studs. I'll have to check.

 

I noted the "taking a good run at it..." part. That's one of the major problems. The hill starts maybe two car lengths out of the garage, and it's at about a 90 degree angle to the garage exit, so there's little opportunity to build momentum before starting the climb.

Also keep in mind that neither of these two (Dad or step-Mom) are winter driving rookies. Anything but. We moved to NH in 1964 when I was a small child, and Dad has been there since. Step-Mom her whole life. That's well over fifty New Hampshire winters for both of them.

What they're really curious about is whether the Gen-4 has any specific issues, with TC or anything else, that weigh against its daily use in icy and hilly terrain. Stories about the Gen-2 car (not sure about the G-3) and its hyper-protective traction control still abound on the internet, and that has them concerned. Sounds like maybe that's less of an issue with the G-4. I've watched one of those Weber State videos on the Gen-4 trans and there are some clues there. It is a new design, no longer a single shaft, and the MGs are geared differently, generally being higher rpm/lower torque designs, that multiply tq via gearing. I don't know whether this info suggests the answer, but I suspect I'm getting warmer (pun intended...).

Anyway, it's not sounding like any Gen-4 drivers are having substantial problems in this regard, but my "investigation" is far from over, so the more feedback, the merrier! Thanks everyone.