I have a 2006 Toyota Highlander Hybrid base model. No 4wd.

Does the electric motor disengage after 42MPH or what. And passing on the Interstate at about 60-70 if you floor it will the electric engine still be able to assist or will it be the V6 engine only/

There is a maximum speed that HSD vehicles can go using ONLY the electric motor after which point the gas engine needs to run. The electric motors can ASSIST the gas engine at any speed AFAIK.

40 miles per hour is the maximum speed that the electric motors can run without the engine also running. Also,when coasting to a stop without your foot on the accelerator, the engine will not shut down until your speed is below 40 MPH.

What?? I can't go more than 15-20 miles per hour without the ICE kicking in. I'd love to keep the engine from starting.

Accelerating up to 40 miles per hour under electric motor power alone is very difficult and it does not use the battery energy to advantage. The ICE is programmed to operate under acceleration conditions in combination with the electric motors. If you accelerate excruciatingly slow you can probably reach above 30 miles per hour if all conditions are just right. The engine is most efficient under a load and moderate acceleration is one of the efficient modes for the ICE. High speed driving with the consequential wind resistance and driving up hill are other efficient modes for the ICE.

If you travel 45 miles per hour and decelerate to just below 40 MPH with your foot off the accelerator, the engine will stop if the vehicle is warmed up and it is not unduly cold outside. You can now get the vehicle to run on electric for a short duration only as long as the terrain is flat - no hills or even a slight incline -and you do not try to accelerate.

I got to 41 miles per hour on just electric the other day and traffic was pissed off.

You really don't want to use the battery pack only for acceleration. My best results are usually when driving in 35-45 miles per hour zones, using moderate acceleration and then cruising/coasting mainly on battery power.

lakedude is correct. From my experience the engine is always running on the highway, but the battery pack will sometimes kick on and provide a little boost.

I'm new here. Can you explain why we would not want to accelerate using only battery power? Assuming that we won't be shot, wouldn't it be a great way to increase mileage?

As a further consideration, because I read that the rx 400h batteries discharge when parked overnight, I try to use every last bit of battery power for my urban driving before parking for the night since the engine usually starts up in the morning regardless of how well charged the battery was the night before.

Thanks.

The battery packs cannot provide adequate power alone.

[quote=mjcmjc;119344]I'm new here. Can you explain why we would not want to accelerate using only battery power? Assuming that we won't be shot, wouldn't it be a great way to increase mileage? quote]

Acceleration usually requires more power than driving at a constant speed. The engine is most efficient at converting fuel into mechanical energy when operating under a heavier load. Since the engine will run frequently to keep the battery charged anyway, it’s best to allow it to run when the power demand is greatest. Why discharge the battery with painfully slow battery-fueled acceleration only to have the engine kick-in for a battery recharge while you are cruising along at 35-40 miles per hour? It’s usually more efficient to accelerate under engine power and cruise under battery power.

Particular driving situations may favor battery power acceleration such as accelerating a short distance to then stop again, or accelerating at the beginning of a long downhill run where regenerative breaking will be used.

As you noted, using up some battery charge just before shutting down is a reasonable way to maximize your mileage if your driving route allows it. I have a 2 mile long, 35 miles per hour run just before the parking lot at the office. During milder temperatures, I run on battery power for just about that entire distance. The battery charge will drop a few bars before I shut down. During engine warm-up on the next drive cycle, the engine will charge the battery which places a greater load on the engine making it more efficient and also warming it up faster.