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Low city mpg on 2006 Prius - is this normal?

Old 01-25-2015, 08:01 PM
Thread Starter
Join Date: Jan 2015
Posts: 1
Default Low city mpg on 2006 Prius - is this normal?

I just purchased a used 2006 Prius, 154K on the odometer (and original electric motor) but well taken care of and still runs great. The highway milage is performing as expected, or even somewhat better - I get 45-46 mpg highway, sometimes more, in spite of the fact that I tend to drive fast where the flow of traffic allows for it. (I'm careful to avoid fast acceleration and a lot of braking, though, which I think probably helps with highway fuel economy.)

What's been an unpleasant surprise is city mileage, though. I've read that city mileage is supposed to be a few mpg better than highway, but in my Prius, mileage *plumits* when I leave the freeway. Yes, I occasionally come off the freeway in the green zone and get some all-electric driving out of that, but that typically goes back to blue within a mile or two, and I'm back to mixed engine and electric driving, even at very low speeds. The city mileage seems to average somewhere in the low 30s, 35mpg tops.

I know that actual performance is often below EPA estimates, but this is *way* lower than the estimated city mileage for this model, and particularly odd, because I am getting the expected highway miles. Is this normal, or is there something wrong with this used Prius I purchased? Is it a symptom that perhaps the battery has lost it's storage capacity and is on its way out?

Right now, I'm keeping the tires inflated to 35 front/33 rear, per the manual's recommendation - I have not yet tried the overinflation strategy I've read about. Is that generally helpful with city mileage?

Thanks for any advice more experienced Prius drivers can give me,

Last edited by pgwerner; 01-25-2015 at 08:07 PM.
Old 02-04-2016, 08:26 AM
Join Date: Feb 2016
Posts: 2
Default Re: Low city mpg on 2006 Prius - is this normal?

Priuschat.com is probably a better place for this, they are far more knowlegeable with the prius and have more active members than this forum.

How far is your commute?? It's also winter time, which kills mileage.

The reason i ask is because the initial warm up time for the prius means the engine will be on all the time for 10+ minutes while it warms up in cold weather. During this time, you'll get maybe 30-35mpg. So if your commute is short in the winter, you'll get very poor mileage because half your commute, the engine was warming up and running the whole time. For long commutes, this is less of a problem. My commute is 1 hour, so 10 minutes i'm warming up, the other 50 minutes it's running normally. So my winter mileage on my gen3 prius drops from 50mpg to about 44mpg. For short commutes, you might see high 30mpg's. People that constantly make short trips will see low 30 mpgs in the winter.

Also, after defrosting your windows, try to keep the climate control at 70 degrees, on auto if you can. Keeping it high will cause your engine to kick on more often.

Don't do the overinflation strategy, low rolling resistance tires already ride like crap(very bouncy), over inflating will make them even worse, and jittery. Unless you simply don't care about ride and want maximum mpg. But considering how cheap gas is today, i'd compromise and favor ride quality.

Make sure you tune your braking strategy to hybrid driving. Meaning, don't be a late braker and wait until your close to the light to stop. Coast to a stop from a long distance away, try to use as much regen braking as you can without using as much pad braking.
Old 02-04-2016, 09:24 AM
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Join Date: Sep 2014
Location: Mesa, AZ
Posts: 3,041
Default Re: Low city mpg on 2006 Prius - is this normal?

PC is a better place.

DO over-inflate. It's worth it. 40/38 IMHO

IMHO, your battery is likely suffering from capacity deterioration. This happened recently on a friend's 08 with 143K miles. I tested his pack and found it was only using 625mAh of capacity in a discharge test (15A average load).

I grid charged and discharged his pack. The same capacity test conducted much more aggressively (25A load) showed the car using > 1600mAh. I re-tested it 6 weeks and 1800 miles later, and it was still using >1400 mAh with an even more aggressive test (35A, with spikes over 100A).

If you go to PC, look my username up (same as here) and follow the link in my sig.

There are other causes for poor mileage, but higher mileage cars (>120K) are mostly likely in need of a new pack or pack maintenance.
Old 07-20-2016, 10:36 PM
Join Date: Apr 2016
Location: Sydney
Posts: 10
Default Re: Low city mpg on 2006 Prius - is this normal?

I don't have a Prius myself per se but I have heard from a lot of friends that when you think your mileage and fuel economy is suffering a little bit, it could really be issues under the hood that causes the car to be inefficient. A friend of mine got in an accident and once his front panel was replaced his car miraculously became more efficient for some reason!
Old 07-21-2016, 06:16 AM
Ridiculously Active Enthusiast
Join Date: Sep 2014
Location: Mesa, AZ
Posts: 3,041
Default Re: Low city mpg on 2006 Prius - is this normal?

Unless your friend has detailed mileage records and is making that statement based on actual data, your friend is wrong.

All too often mileage is influence by weather or driving habits. Maybe the shop simply aired up his/her tires...
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