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Discussion Starter · #1 ·
just had a rear end repair done
car was in the shop for about 20 days
they had to disconnect the hybrid while doing the repairs
the accident should not have damaged the batteries or the hybrid

so what has happened to my fuel economy?
lifetime is about 4.8L/100km
since getting the car back 6.0L/100km (no air con)
 

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Have the dealer inspect the HV battery??

Poorer mileage would mean the engine's running more often which means the battery isn't providing boost as often as before so....
 

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If the rear end was done, make sure the rear wheel bearings and brakes are ok. If for example the brakes are improperly adjusted (rear drum brakes in North America), they can drag and decrease mileage. The best way to check is to jack up the car (block other wheels well since the brakes have to be off!), and see if each of the rear wheels spins freely.
Also have alignment checked?
 

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Michelle, are you implying that there is actually some kind of AI learning going on here? I thought the break-in period was purely a mechanical thing... stuff loosening up and moving more easily. If there is some kind of adaptive learning, how does it work? What does it look at?
 

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I don't know specifically about the Prius, but most (all?) OBD-II cars learn and recalibrate their stored values, which get reset to factory defaults when memory is lost (like with battery disconnection). Even in a closed loop system, there are many parameters that control deceleration, power mixture, reactions to temps and air pressure, etc., that get learned by repetition.

I believe this may be why many have noted initially poorer mileage after an ECU flash; it has to learn again and should settled back into the old MPG patterns after a few dozen runs.
 

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I agree with mrv. In my observation, after 2500 miles, the Prius MPG improves suddenly in my case from 46 to 48mpg. Temperature is not a factor in California. My daily route is the same. I also strongly suspect that a "learning curve" goes on in Prius' computer.

Other factors may be the alignment or brake pads. I just had my front brake pads replaced in my BMW. The mpg dropped to 15.5mpg (yeh., its's a V8). After about 500 miles, it is now back to 16.8mpg. Again, same route in comparison. Just FYI.
 

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Have you check your tire pressure? Perhaps the mechanics inflated them to their "specs", which I find too low. From what I've seen, the difference between 35 psi and 40 psi is at least 10% worse MPG. I run at 42/40 front/rear and don't find the ride stiff at all.

Also, what does the car feel like when you are coasting. If you are driving and put it in neutral, does it feel like it's rolling OK, or does it feel like it's dragging? This might help you figure out if there's a bad bearing or the brakes are sticking.
 

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Discussion Starter · #10 ·
thanks for all the help



Have the dealer inspect the HV battery??
had this done today and according to the diagnosis everyting is ok

Does BC use a "summer gasoline" formulation? That can increase fuel consumption.
i really don't think so and i hope not

If for example the brakes are improperly adjusted...
that is a strong possibilty, i noticed the car seems to slow down very quickly when letting go of the accelerator

you're in break-in mode again...
i wondered about that but when the hv batteies were replaced about 3 months ago there was no change in the fuel consumption. of course that took only one day while the body work this time took 20

does it feel like it's dragging?
yes it does a little but i wonder if it's because i'm also re-learning to drive the prius. i didn't drive it for almost a month and it felt even stranger than when i first drove it 8 months ago [/b]
 

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av_in_bc said:
you're in break-in mode again...
i wondered about that but when the hv batteies were replaced about 3 months ago there was no change in the fuel consumption. of course that took only one day while the body work this time took 20
Disconnecting HV battery won't erase anything, but disconnecting the aux battery for a significant time might.

However I am betting on brakes and/or alignment.
 

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summer formula gas will increase your mileage. i think its the tires and alignment too.

also more than a few people have reported getting a software update and having reduced mpg's afterward
 

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I am betting on rear end damage that was not repaired

I have to bet on rear end damage that was not repaired, or the brakes are dragging. The mechanics will think you are nuts, but if you press them on checking the rear end I am betting you will find something wrong.

I remember my first car was rear ended and it took months of going back to convince them that there was rear end damage to the drive train. When a car is shortened by a foot there may be more wrong than needing a new bumper.
 
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