Battery Acceleration

[StephRG]

Hi,

I would like to confirm that the behaviour I'm experiencing is normal and other P3 owners are seeing the same thing.

It's hard to explain so don't hesitate to ask me for more details if I'm not clear enough.

In Eco/normal mode (not sure about power):

I don't really see any impact on how much I press the gas pedal as long as I'm below petrol motor kicking in.

If I barely push it (so displaying a few pixels on the ecometer) or further down (up to the middle of the ecometer) I don't feel any difference.

0-10/15 Mph: The car accelerate after that from 15 Mph I can barely see any increase in speed at all.

While above 30Mph if I stay in the first half of the ecometer (I see energy getting out of the battery) I don't see any difference with being in neutral (being gliding or forcing the N gear).

I just would like to confirm if that's the expected behaviour or if I have something wrong, especially as my average MPG is below my expectation: around 55 MPG in country roads (45-55MPH pulse/glide only 50 MPG otherwise), 45 MPG on motorway (70 MPH (real-Tomtom, 77 MPH on display)), cruise control).

No real MPG difference between eco and normal.

Thanks,

Stephane

[timberwolf]

Why are you try to accelerate on Battery power alone - it is generally not a fuel efficient way to drive a Prius.

[DrCez]

I would like to confirm that the behaviour I'm experiencing is normal and other P3 owners are seeing the same thing.

Hi Stephane, I haven't checked really carefully but these are my impressions in my Gen 3 car

- low speed behaviour sounds similar to my experience, i.e. above about 15 mph it gets much harder to keep the ecometer (hybrid system indicator or HSI) below the half-way mark.

- from 30-50 mph I reckon on a level road the car can maintain speed without pushing the HSI into the second half, but as soon as conditions are not favourable (slight incline, headwind, ?wet weather) it will need a bit of extra juice.

I'm not too worried about this behaviour, IMO the car is choosing to use the petrol engine once it is going fast enough. As timberwolf points out the electric motor is not very fuel efficient because the energy it delivers has gone though several conversions with some losses at each stage. There is a lot of detail on what the Gen 3 HSI can tell you about the car over on the PriusChat forum - see this thread.

That said, I haven't done any driving at motorway speeds but on the few occasions I've been out on country roads the MPG (reported by the car) was more like 60-65 (without trying particularly hard to drive efficiently). I had the impression that you might expect better than 45 MPG on the motorway - I'm not sure how much difference the last 7 mph to get you up to a true 70 mph is making. If you're using anything else that uses the Battery (a/c, demisters, etc.) I suppose that might make a difference too. Some people post their average mpg here and I think they are generally a bit higher than what you are getting - it would be interesting to hear what typical motorway MPGs other members are achieving.

[Sagitar]

it would be interesting to hear what typical motorway MPGs other members are achieving.

I drove from Melksham in Wiltshire to Ampthill in Bedfordshire today. I filled the tank and re-set the trip last night. The journey included 70 m.p.h. driving on the M4 with the cruise control set and further cruise controlled 70 m.p.h. driving on the dual carriageway from the M4 to beyond Oxford and for a short distance on the by-pass around Tingewick. All the remainder of the journey was at the limit allowed, mainly 50 and 60 and much of it with cruise control set. At the conclusion of the journey, the trip was showing 62 m.p.g.

It has never been my intention to agonise about mileage. I want to drive fairly briskly and get to where I am going without wasting too much time. It seems to me that the Prius allows me to do that pretty economically and also gives me good economy in local stop-start traffic.