I have a lot of trouble getting the glide, but I found a cheat mode. If you put the car in neutral, you go into no bars mode, regardless of the speed. This may be a way to get P&G at higher speeds.

I know in a normal automatic car it is bad to go into neutral while moving (as oposed to the stick where it happens all the time). However, I dont think this would be true in the TCH.

In the auto, part of the problem with ging in and out of neutral is the sudden linkage with the transmission. Since the TCH uses a CVT, it doesnt seem like this works the same way.

Also, When going in and out of neutral, I dont feel any jarring, the drag from the normal regen just kicks in, and then I hit the gas.

Thoughts? Is this bad?

 

It's an interesting idea. The idea of glide is to minimize the power transfers, which are inefficient. With the HSD system putting the car in neutral disconnects all the power sources from each other.

My concern is that it seems too obvious. Unless this doesn't work or would cause harm to the system it seems the group that got 109 mpg from the Prius would have exploited it a long time ago.

 

I don't find the drag on this car to be very high. I'm guessing the distance you can glide in "N" is not much further than what you get in "D" and you'd get no benefit from regen so that when you do accelerate back to speed you're doing it all with your ICE.

I don't really think "pure" gliding is safe on most roads. I just took another trip tonigh of 45 miles and averaged 46 mpg. I did it driving 40 to 45 on a rural road that parallels the interstate (where I would typically get 38 mpg on the same trip). That probably doesn't save me a lot of money, but it doesn't take that much longer, there is no traffic and it's more relaxing. However if I was gliding from 45 to 30 over and over that would not be relaxing. I'm pretty fanatical about the FE thing but I'm not "over the edge" yet and don't see me practicing that style of driving.

 

Joe,

How do you get that kind of mileage doing 40 - 45? I find that's about the worst speed for good mileage; too fast to use EV but not fast enough to get highway mileage.

 

Unless drivetrain efficiencies start going down substantially above 45mph there shouldn't be any need to drive faster to get better mileage. In general (and I realize hybrids, especially HSD, are a bit more complicated) you get the best mileage at the lowest speed you can drive in the highest gear ratio. I've been playing with that for a long time in my conventional vehicle and the effects are pretty astounding, though things get a little foggy with hills and acceleration. It's all about the energy...the lower the resistance on the car (which is mainly aero drag at higher speeds) the less energy it needs to produce to keep moving. Hence, less fuel needs to be burned.

I'm curious...does anybody know just how slow a TCH can travel and still maintain something of an overdrive gear ratio between gas engine and wheels? (I already know some smart aleck is going to say 1mph because EV mode = infinity ) Probably not an easy question to answer, but that would be a valuable thing for you guys to play with in a controlled manner.

 

How do you get that kind of mileage doing 40 - 45? I find that's about the worst speed for good mileage; too fast to use EV but not fast enough to get highway mileage.

On the highway (65 to 70mph) I'm usually able to get 37 to 41 mpg, depending on the terrain. My trips from Jane lew WV to Charleston average 41 when I drive, 38 when my wife drives. There are sections of that road (4 lane interstate) where I can only get 35 for several miles.

My rural milages are a lot better than my city or my Interstate milages. What I'm seeing is when my ICE is on, for the most part it is driving the wheels AND charging the battery. My battery obtains the GREEN charge a lot and when I do go down hills and across the level areas before the next hill I am either in E mode or getting 60 on the scale.

Again last night I took a trip from Jane Lew to Bridgeport (45 miles round trip) and took the back roads. No stopping, paying attention simply to the Instant FE gage, I would get up to 45 -50 mph and let off the gas. I immediately reapply the throttle lightly and am able on level ground to maintain that speed with a FE in the 50 to 60 range. As I start up slopes the FE starts dropping, I may or may not lighten up on the gas. I do if it helps me stay above the 40 mark but if it starts dropping in to the 30's or 20's I use that time to pick my speed back up and let off the gas again before I crest the top of the hill. Typically I can then "glide" down the hills with the 60 reading.

It's a constant operation, but after a while you don't really have to monitor the gages constantly, you'll get the feel for it. However it does require lifting the foot often (several times per mile). Even on flat's you'll sometimes feel the ICE helping out and see the gage drop and I'll either let off to see if I can maintain reasonable speed OR again, I take that opportunity to speed up. I figure if the ICE is going to rev and get 30 mpg, I may as well accelerate and get 20 instead but in turn get my speed up so I will be ready to glide some more.

I typically can maintain the speed within a 5 mph range doing this. I never even considered it until I saw someone post that they got 50 mpg. I didn't think that was possible unless you were just driving around in EV mode. I've tried it on 3 trips now ranging from 25 miles to 45 miles and was able to get 46 to 56 mpg. These are not mountains I'm climbing, but they are the hills of WV and I can't avoid them.

I'm going to Columbus (flat land) this weekend. I'll be curious to see what's possible there.

 

Joe,

Thanks for your answer. I'd also be curious to see how it works out on flat roads. With the exception of overpasses that's all we have here. I do find that if my SOC is high I can get that type of mileage in the 45 - 50 mph range, especially since the motors will kick in every so often to reduce the charge and thereby the work of the ICE. Perhaps the downhills causes your SOC to get high enough that that's what's happening to you.

Please keep us updated as to what you find on flat terrain. And if you can figure out what specifically to do and not to do will you offer a course.

 

In general that's true, but not necessarily for a hybrid. Toyota's HSD does not use anything remotely resembling a regular transmission. Instead it uses the ICE, motor/generators and a power split device (PSD) to perform the same function. For the most part while cruising along running on ICE (above 42 mph) the engine will run at a constant RPM regardless of speed. That means it's using a constant amount of fuel per second so the higher the speed the more distance you're covering for that amount of fuel. It's not until the speed gets higher that the aerodynamic drag starts becoming a major factor (guessing at 65 mph) and fuel efficiency starts decreasing as speed increases.

 

Originally Posted by brick
In general (and I realize hybrids, especially HSD, are a bit more complicated) you get the best mileage at the lowest speed you can drive in the highest gear ratio.

My best milage results are in the 40 to 50 range

 

And to add to that, I find it's not necessarily consistant depending on the road. At ICE required speed (45mph+) sometimes I find driving 55mph gets best FE but othertimes I've seen getting crappy FE at that speed and it improves quite a bit going up to 65-70mph.