I apologize if I'm asking an old question. Perhaps I have been asking the wrong question which is why I have been unable to find the answer.

I have a 2005 FEH and when i'm not city driving i'm doing 60mph on a mountain highway. I'm frustrated with the fact that the car will not switch off the ICE at this speed. after 1000 vertical feet of climbing and a 1000 foot descent coming up it would be nice to see it switch to EV.

Is there a good reason for having an automatic switch at 40mph ? Is there some way besides FAS to change this?

Thanks....

Yes there are good reasons for this, and yes they have been discussed, but may be buried deep on here somewhere. I'll give you the short, short version.

You have a planetary transmission. Kinda like the rear differential on a car. With two wheels on the ground, both wheels spin the same direction, and at the same speed. Take one wheel off the ground ( or put it on gravel or ice ) and it will spin faster than the other, or even reverse, while the other one slows down, or stops.

The electric motor has a max. RPM. It reaches this max. RPM at 40 MPH when the engine is off. When the engine starts, ( speeds up ) it is like lifting a wheel off the ground in the above example. Thus, the electric motor can slow down. It is now under the max. RPM and can still deliver torque when called upon to pass on the highway.

Does that help?

Thanks for the explanation. I could swear when i was test driving a Prius last year the ICE would still shut down at speeds greater than 50mph. Is the 40mph of the FHE on the low side compared to other hybrids?

The Prius was limited like the FEH in '05 I think, but I just learned the HiHy could shutdown the ICE at those higher speeds also. More than likely, Toyota has overcome the 40mph limit now in all their newer hybrids.

GaryG

Newer Hybrids will have a "2-stage" transmission. Kind of like a "hybrid high, and hybrid low" setting. Thus, they are much more flexible, and can do EV at higher speeds... perhaps the full range of travel speeds.

I do not think the Prius is so equipped... yet.
And I think the Highlander is still "old school" transmission, but may have had more range all along.
I think more like MY 2008 or 2009 will have the newer transmissions.
And future Fords will implement this as well... starting with the Ford Fusion and Mercury Milan Hybrids. ( word on the street )