There is something I particularly like about the Prius - how it behaves at low speeds. The car seems to react much more linearly to the accelerator at low speed than the other cars that I have driven. This makes it particularly handy in heavy traffic, and for parallel parking on hills. You want to move the car a little - just press a little on the gas. The car can be moved with precision. I love that. Now something strange hapened to me twice this month. I think I got the explanation - I just wanted to confirm my hypothesis. Perhaps you have a different opinion. I leave the office at the end of the afternoon - the ICE is cold. I drive for 10 meters - the ICE starts. I merge with the boulevard, then climb a low grade hill for 50 meters. I keep my foot at a constant level on the accelerator. There is a slight acceleration, fuel economy display is steady, ICE is running quietly. Speed is about 30 km/h. Then, all of a sudden, I get a surge of acceleration - not major, but very noticeable. The ICE seems to have suddenly "woken up". I see fuel economy rise to the top of the display, the engine is noisy, and speed increases much more quickly. Today it happened, for the second time this month. This time I noticed the battery level when it happened: it showed 2 bars. My hypothesis: I learned in http://priuschat.com/forums/gen-iii...992-warming-up-engine-batteries-downhill.html that when the ICE is cold, it does not provide much power to the wheels, unless you really press on the accelerator. So when you start with a cold engine, the car is mostly running on battery alone. Today when I started the battery was 4 bars. Then I drove, climbed a little hill, and used A/C. It drained the battery down to 2 bars. Then I guess the system realized it could no longer run on battery alone, so it requested power from the ICE, making it run much quicker. Would that make sense? The feeling was strange, as I felt for the first time that I did not have full control of the car. The reaction to my constant pressure on the accelerator was quite unexpected. Because normally, when the ICE kicks in during acceleration, I barely notice the difference in acceleration. Opinions?
The OP's explanation is correct. A cold ICE mostly burns gas to warm up, providing little power to the wheels unless you force it. Tom
I have had occasion to push mine when cold a little more than usual (I'm running late in the morning, getting accustomed to earlier working hours) - there is a definite surge as the ICE comes on - I wouldn't call it "sudden acceleration - just a more noticeable transition as the ICE kicks in.
I have this (sounds the same anyway) happen quite often myself. I can almost force it to happen at will and the engine is not cold. There is a hill a couple of miles from the house and I accelerate up to it and let off the gas to coast down it. As I lift off the gas there is drag to a certain point and then the car all of a sudden "free wheels" which seems like acceleration (especially since it is heading downhill). As the car exceeds 46mph or so, I can feel/see the ICE spin up and then the "drag" is back. Like the OP said, it isn't a huge surge but noticeable. Like I said, I don't know if it is the same thing but it sounds like it.
Thanks. I really did not know how to call it. I realize "sudden acceleration" is not ideal, just the best my french speaking mind could find...
Mine does it all the time. Did it this morning in fact. I find that it only happens on cold starts when the engine is going through the early warm up stages. If you keep below the power band, the engine is running, economy is running at 50 mpg (uk) and performance is down a little. Push it into the power band however gently and there is a slight surge and the car accelerates as normal and the economy does drop to about 25 mpg however hard you try. Once the car has warmed up past this stage in a couple of mins all is back to normal. Is it to do with the stage where the ICE is powering the car via the motors and then when you push it a little more it starts to drive the car as normal? (excuse my non technical talk).
