You will not get 50 MPG if...

[LRKingII]

Originally Posted by martinw

One thing I'm finding is that coasting downhill, even with the regen, the car loses less speed than other cars. I guess it's not that surprising given the aerodynamics, but I thought the regen would cancel it out. I'm finding I spend a lot of time on the brake on long downhills when following other cars that are coasting, even slipperly looking sports cars.



What happens when the battery is fully charged? I assume the regen system is still operational, so how and when does the extra energy get discarded?

When i do it in cruise control on a 7 mile long 6% grade hill the ICE kicks in and acts like a air pump i think you call it and holds back the speed. Dunno if this answers your ? or not.

[windstrings]

Originally Posted by martinw

One thing I'm finding is that coasting downhill, even with the regen, the car loses less speed than other cars. I guess it's not that surprising given the aerodynamics, but I thought the regen would cancel it out. I'm finding I spend a lot of time on the brake on long downhills when following other cars that are coasting, even slipperly looking sports cars.

Interesting!.... maybe they backed it off a bit for the 2010 to make it a tad more efficient!....
I see no problem with having to lightly touch the brakes..... unless the 2010 is different.... a 50K regen generator kicks in when braking.. when coasting, its a 10K... so no foul to have to lightly apply the brakes.

The car has a few different ways of wasting energy when needed.... sometimes it will maintain movement of the pistons....even while sitting still! without fuel being supplied to the engine..... I'm not the guru on that subject but its never a problem.

The logic obviously changes too to use battery when able.. but if your coasting down a very long hill, the engine will turn over to waste energy if there is no place else for it to go.


What I don't know is... does regen continue to work "thus saving the brake pads" and simply waste that regenerated power, or does the regen drop out and you go to friction braking.... I don't think the latter is true.. at least I've never read about that being so.
In those situations.... the "B" on the shift lever allows the engine to burn up some of the kinetic energy with the compression of the engine if I remember right so the car doesn't have to deal with it some other way....ie:" braking, regen etc.

[PriusRos]

Originally Posted by wfolta

None of this means you're a bad person. It's just meant to give some thoughts on why you might not be getting EPA mileage (or better) in your driving. As the ads say, YMMV, and even if you don't achieve EPA, you're probably getting better mileage -- for the same geography, climate, weather, and driving style/habits -- than any other car you might choose. For your consideration, you probably won't get 50 MPG if...

1a. You drive 5 miles to work. The car gets relatively low mileage while warming up, so you take a big mileage hit at the start of every trip, and need to run long enough to overcome that initial deficit.

3c. You go uphill to work, then uphill again to home.

I'm guilty of 1a and 3c . But I'm getting around 47 mpg whereas I only got around 43-44 on my previous prius. Can't tell for sure yet since I'm still on the first tank. I did get something like 57 mpg when I was driving on the highway for a while.

I find the what really eats mileage are lots of stop and go traffic, such as at traffic lights, rain, hills, and short trips.

[cossie1600]

I did drive on teh highway a lot, at pretty high speeds, that might have something to do with it. Still, 50mpg, I think you either have to be super careful or drive so slow that people are probably going to curse at you.

I guess the ones getting 60mpg are the ones running the slow lane at 40mph

[rachaelseven]

Longer trips, in slower speed areas (most speed limits are less than 40mph here, for example), makes it easy to get high 50's while keeping up with traffic in a very normal way. Higher speeds, shorter trips, and crappy weather will all lower mileage.

[fuzzy1]

Originally Posted by martinw

One thing I'm finding is that coasting downhill, even with the regen, the car loses less speed than other cars. I guess it's not that surprising given the aerodynamics, but I thought the regen would cancel it out. I'm finding I spend a lot of time on the brake on long downhills when following other cars that are coasting, ...

Put it on Cruise Control, as LRLingII and I do. That will boost regeneration to create enough drag to maintain constant speed. That is, until ...

What happens when the battery is fully charged? I assume the regen system is still operational, so how and when does the extra energy get discarded?

That power is used to spin the ICE, in compression braking mode. Because the ICE is small, is spins quite fast, sounding like a giant vacuum cleaner.

Originally Posted by windstrings

... What I don't know is... does regen continue to work "thus saving the brake pads" and simply waste that regenerated power, or does the regen drop out and you go to friction braking.... I don't think the latter is true.. at least I've never read about that being so. ...

In Cruise Control or 'B' mode, the Regeneration bar in the HSI display goes to zero, while the ICE starts whining at high rpm. In manual braking mode, the Regen bar is completely filled, but the car is using purely friction brakes, because it cannot regenerate without some place to dump the power.

In the past three days, I've descended 6 different mountain grades in western and central Washing where regeneration completely filled the battery, forcing high-RPM engine compression (in CC or B modes) or friction brakes (manual control).

Originally Posted by LRKingII

When i do it in cruise control on a 7 mile long 6% grade hill the ICE kicks in and acts like a air pump ...

Is this the Lewiston grade? I skipped it on the way in on my most recent Idaho trip, taking Alpowa instead, but will descend it on the next trip. I did leave Idaho by climbing up this grade at speed limit, as my first high power Prius test. It had 1200 rpm to spare. A couple drivers did look surprised to see a Prius flying by them uphill.

[fred garvin]

i am getting 59 on my current tank (up from 54, 57, 58) and i drive plenty fast

i drive five miles on hilly country roads to get to the greenway, where i drive 13 miles at 70 mph (limit = 65). then I drive 13 miles on the toll road/66 at 64 mph (limit = 55). Of course there are some slow downs and speed ups, and i am in the HOV lane.

My method is to take off in eco mode, and try to delay the ICE. If somebody is behind me i accelerate much faster as i hate to hold anybody up.

Then when i get off the battery only, i punch it into pwr mode and feather the gas so the hybrid system monitor bar is right at the point of being in the "power" red zone and i accelerate fairly rapidly to the desired speed, wher i punch the button back to eco and try and then manage as best i can.

[anne1965]

Originally Posted by fred garvin

Then when i get off the battery only, i punch it into pwr mode and feather the gas so the hybrid system monitor bar is right at the point of being in the "power" red zone and i accelerate fairly rapidly to the desired speed, wher i punch the button back to eco and try and then manage as best i can.

That's a lot of switching back and forth. I'm lazy. I just put it in ECO and when I need more acceleration, I press a bit harder on the right pedal. Even in ECO mode there is more than enough power to keep the drivers in the rear view mirror happy.

And I have accepted that some drivers are never satisfied with your speed. That's because they always want to go faster than you, whether you are doing 60 or 100 or 160 (kph that is).

[anne1965]

Originally Posted by cossie1600

I did drive on teh highway a lot, at pretty high speeds, that might have something to do with it. Still, 50mpg, I think you either have to be super careful or drive so slow that people are probably going to curse at you.

I guess the ones getting 60mpg are the ones running the slow lane at 40mph

Hmmm, mine does 60 mpg @ 60 mph.

On the highway I always keep my CC locked at ~97-98 kph (=61 mph) and the consumption is then around 3.5 l/100 km. Counting with a 5-10% FCD inaccurracy, that's more than 60 mpg. But we have no mountains where I live... And no 40 C heat. But we do have wind, lots of it.

[PeteJE]

Buy a light one without all the options.

Those of us who can barely afford even the base II are really just mileage purists, LOL.