Need some answers

Are you certain that the car actually rolls some distance, as opposed to just jerking as the ICE starts?

You've piqued my curiosity: do you spend a lot of time with the car ON and in PARK? If so, why? (I hope it's not to warm up the car in cold weather; that is completely un-necessary, and wastes gas.)

 

I guess it depends on your definition of "very good jolt."

Then the car is in park, the transmission is mechanically locked, but there is a little bit of play in the locking mechanism. You can demonstrate this by rocking a car that is in park (but doesn't have it's parking brake on); the car will roll forward and backward an inch or so.

Think of it as having wheel chocks in front of and behind the wheels, and there is a little bit of a gap allowing you to rock the car. If the car is resting against the rear wheel chock and the ICE starts, there is a small amount of torque that will transmit through the Power Split Device and make the car roll forward. It will hit the forward chock, stop, and then roll back to it's resting position on the rear wheel chock. If the parking brake is applied, you might feel the ICE kick on, but the car should not roll forward. It is probably only happening 8 times out of 10 because the 2 times that it doesn't happen the car is on more of an incline, and is firmly resting against the front or rear "wheel chock." The reason that this doesn't happen when you are in Drive, is that unless you are moving, you are probably holding the car stationary with the brakes.

All this said, I've noticed the same thing on my car when I'm parked in front of my house. I'll press the power button and sometimes I won't immediately put it into Reverse because I'm putting something away. The ICE kicks on after it's slight delay and the car rolls slightly forward. I wouldn't call it a "very good jolt," but that is just my perception. It would be great if you could find another Prius owner nearby that you could compare cars with.

 

I've been jolted too! Twice thus far and both times while getting coffee! Typically I'll put the car in park while waiting in the drive-thru at the local coffee house. The first time I nearly peed my pants, as I thought the car was going to drive away with me and/or hit the person behind me. It's not a huge jolt, but it sure is felt! I've started leaving my car in drive with my foot on the brake and voila no more jolts!

 

I assume that the jolt is due to the initial torque of the ICE being turned over by the starting motor. Since the ICE is mounted across the car, the jolt would be felt along the car as a fore and aft motion. Hence, the car feels as if it is moving slightly as the ICE is started. My 2005 jolts also, so I doubt if anything is wrong. Although, it was a bit surprising initially, when you were expecting the car to behave more like a golf cart....

 

Do you have your foot on the brake when this happens? The only time I felt a jolt of any sort was when I put on the parking brake, but took my foot of the regular brake then pushed Power to shutdown.

 

I've had "the jolt" maybe 6 times since buying the car, most recently in colder weather. I've noticed it's most likely to occur before the ICE is fully warmed up. If I drive for an hour or two at 110 km/h, then go back into the city, the ICE shutdown and startup is almost imperceptible.

 

I too feel a "Jolt" on the first startup for the day. My perception is not that the car is rolling any distance, but more like the feeling you get just after coming to a stop where the wheels are not moving, but the car body still has forward momentum energy and then the car sits back on its haunches. I think this may be normal for a Prius . . . but it wouldn’t hurt to ask your Prius mechanic next time you are in.

If your Prius is "jolting" enough to spill coffee, I think you have three problems to be addressed.

1. Car HSD problems
2. Car interior cleanliness.
3. Low caffeine intake! This condition can be detrimental to proper operation of a motor vehicle, especially during morning commute hours.

 

i notice a bit more shuddering when the ICE runs now that the weather is much colder now, but i have to say that what i feel is nowhere near the term "jolt"

in fact, its really not that much of a shudder either. ive only just past 7k miles, so i'll start watching it to see if its getting worse.

 

I have 1020 miles on my car and as stated I've been jolted a couple times. I figured it was normal.