I don't know if this has been posted, but I thought I would share anyway. Today, I was going up a hill and hit the top around 40mph. I let off the accelerator, and it dropped to E mode. I then shifted into neutral to see what would happen going down the other side. Imagine my surprise when it stayed in E mode even at 55 mph in neutral!! I'm sure I'm not the first person to figure it out, but I thought I would post anyway. The ICE never came back on either, as I coasted up the next hill. I wonder how fast it can go in E mode, in neutral.

 

Am I missing something here?

What did you expect it to do?

In neutral you are placing no demands on the system period. It would stay in E mode no matter how fast it went downhill.

 

Correct, no limit in neutral when coasting in neutral. I found a great place to coast. It's from Mescalero, New Mexico all the way to Tularosa. Mescalero is 15 miles southwest of Ruidiso.

There is a unadvertised Mexican food restaurant about a mile southwest of Mescalero, north of the highway. It's called the Old Road Cafe and is hidden behind a wooded area. We eat there often. One night about 8 pm we left out. I was in the EV mode. The car was slowly speeding up to 40. I decided to move the lever to N. It kept speeding up to 45 then 50 and 55. We hit 60 and once 70 going down to cross a river where the road turns into the new surfaced highway. Their were 3 places where the car slowed to 42, 43 and 44 miles per hour.

That coasting ended up being 15 miles in all. I had to slow down entering Tularosa. I put the car back in drive at 55 mph then used the brakes to slow down to the 50 mph speed limit. Their is no regeneration with the brakes while in neutral although the physical brakes would work. The engine heat went from 180 down to about 120. It was a cold night and lots of cold air under the hood for a good while. I did pick up about 5 mpg. That more than made up for the 20 and 30 mpg during that 16 mile climb to the restaurant.

A caution when coasting is your using the smaller mechanical brakes. No regeneration at all till your back in the Drive. That night the battery pulled down some with the headlamps. I kept the heater on low fan and about 73 degrees to stay warm.

After writing this I did lot of phone calling around. I found that the generator is submerged in transmission fluid and is cooled by it's own radiator and antifreeze. There is a drive chain in the transmission that turns all the time. That helps lubricate everything. Evidently the power spit device (cvt) is partially submerged and may also get it's lubrication this way. I have done that same 15 mile coast about 5 times with no problems in neutral. Before I was driving rather slow on the slower grades down to keep the car in the EV mode. Its a wide 4 land highway with not much traffic. Any anticipated stops or problems it only takes a second to put in back in drive.

I would say the only caution would be in keeping the display on the battery/engine page. Never allow the traction batter to go below 40%. Glance at it occasionally when coasting then at 40% put it back in drive so it can charge. We were coating at night, during the day the battery should not use hardly any current except for air conditioning.

 

I figured the ICE would turn on, and go back to 'fuel cut mode' when it went above 42mph. That is the first time I have ever seen that happen. I will be doing that from now on if possible!!

 

I am not an expert nor a mechanic, but I wonder if the car was intended to be used in this fashion, or if there could be an unintended consequence. I don't really understand regular transmissions, let alone the CVT that these cars use, but here is my concern...
The transmission (if I understand it...and I don't) is spinning all the while when the car is in gear and in motion. When power is needed, the hybrid's transmission smoothly connects to the engine and is designed to handle this transition.
When you are coasting in neutral, you've disengaged the connection to the engine and when you reengage, by putting it in gear, you are manually connecting the transmission to the engine, in a fashion that it wasn't intended nor designed to be done.
Here is my concern. The transmission is designed to connect to the engine when it isn't spinning, when the car isn't moving. By putting it in gear while the car is in motion, you are trying to make the connection to the engine while it is spinning. Manual transmission cars have a clutch which is designed to make the transition. These cars don't have a clutch. Are they designed to have you 'pop it in gear' when the car is doing 20-30 miles per hour?
Could this action ultimately cause damage and give up the pennies saved in gas with a costly repair bill?
(penny wise...pound foolish?)
Again, I'm no mechanic and I don't know if what I said makes any sense, but I wonder if putting a car into gear in a method that it wasn't intended to could cause problems. Am I wrong?

 

I am not sure that is the best thing to do to increase your mileage. Just as in a traditional transmission, it is not normally a good practice to drive in neutral. I mean.......you have no directional drive control over the wheels while the transmission is in neutral. Plus shifting back to "D" from "N" at any speed other than at a complete stop i would thing is not a good thing to do. You may be asking for problems doing that ..........just a thought!

 

This "trick" is a bad idea. When in other than D or B the engine will spin over 40mph to protect the MG1 motor from overreving. Also, the N position will prevent any regenerative braking (all braking is done with the conventional brakes) increasing brake wear and decreasing mpg. There is also the safety factor -- you cannot apply power if you need it.

 

I don't think it's bad for the engine. I've been shifting to neutral on long downgrades on all my cars, never had a problem. I don't think the engine is moving at all, otherwise the mpg needle wouldn't be in "E" mode.

 

If your over 40 miles per hour and shift into neutral the engine will remain spinning at about 1000 rpm. If your cruising below 40 miles per hour in the EV mode and then slap it into neutral, you can go as fast as you dare (within reason) down a hill and the engine rpm will still be zero. I think the issue over- revving MG1 is overstated. Prius owners have documented MG1 rpm's of about 9800 rpm at about 68 miles per hour using their CAN-view (sorry I can't find the exact reference). I believe the max rpm of 10,000 for the MG1 is the same in both the camry and the prius. I personally wouldn't want to push the car over 65 miles per hour in neutral for fear of melting something. Has anyone gone over 70 miles per hour in neutral? -Ed

 

Hmmm......

Why would the fuel consumption be different?

If the car were at 55mph in drive (with your foot off the gas), it would be in fuel cutoff mode, so would be consuming 0 fuel, the same as if you have it in neutral. Granted, you've lessened the drag, but at the cost of no regeneration. This might be a better trick in a non-hybrid car.

Later!

Dang