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Discussion Starter · #1 ·
From various online comments the Prius average mileage seems to be 45-48 mpg. My 2004 Prius runs great..I love it.. But my mileage runs around 38 mpg. I don't drive hard..have very few hills to climb and live in a warm climate. I haven't been in for any service work so far. Does this ring any bells with anyone..?
 

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Lots of factors can affect your MPG. Some to think about in no particular order

There's a break in period.
Tire Pressure (some say 42/40 beats what's on door plate)
Trip Distance (short trips are bad)
Driving Style
Wind direction (head-winds suck)
Cosmic Rays
 

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Discussion Starter · #3 ·
Thanks HB. I've considered all of your suggestions except Cosmic Rays.. This is S. CA..... My car came from dealer with 44 PSI in all 4 tires. I bled them down to 35. Ride much improved. My trips are generally short but here in SD it never gets very cold.
My first few tanks ran around 45 mpg then it just dropped to around 38. Nothing changed. I'm not an MPG nut. I just want to know it's tuned properly. I'm coming up on 5000 miles so I'll ask the dealer when i get the oil changed. But I get the "feeling" they don't really understand this car either. JD
 

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JDavies said:
Thanks HB. I've considered all of your suggestions except Cosmic Rays.. This is S. CA..... My car came from dealer with 44 PSI in all 4 tires. I bled them down to 35. Ride much improved. My trips are generally short but here in SD it never gets very cold.
My first few tanks ran around 45 mpg then it just dropped to around 38. Nothing changed. I'm not an MPG nut. I just want to know it's tuned properly. I'm coming up on 5000 miles so I'll ask the dealer when i get the oil changed. But I get the "feeling" they don't really understand this car either. JD
Your tire pressure can definitely impact your mpg. 35 PSI sounds low. At a minimum go with the recommended pressures posted on the driver's door. Short trips also affect mpg. The first 5-10 minutes of driving are probably the least efficient with the Prius. Caution the dealer not to overfill the ICE when changing the oil (use about 3.5 quarts). Overfilling also reduces MPG and can damage the ICE if the overfill is excessive.
 

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If your not getting the 45 MPG average with the door pressures (35-33) I would stop in at a different dealers for a talk. I pay no attention to my way of driving or the MFD but I have been averaging the 45 for well over a year. Those pressures are critical. Every service I've gotten at Toyota they've put in 26 all around until door pressures were requested. The first time it happened my milage dropped 5 mpg. Once back to the pressures for the Prius specified, (in the manual, "door") my milage returned to the 45. I don't care one bit for the ride experienced by the higher pressures, but whatever mentally pleases you.
These dealer problems are going to be with us until 90 % of the cars at the dealership are hybrid I'm afraid. For now that's the penalty for our desire to be "different."
 

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Also, at your first oil change, double check the dipstick before you leave. They have a tendency to overfill.
 

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Tideland Prius said:
Also, at your first oil change, double check the dipstick before you leave. They have a tendency to overfill.
And your second oil change, and your third, and your forth
 

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I suspect your problem is your trips. You say your trips are short, but you don't say how short. Driving your car for less than 5 minutes with the AC running high will give you about 35 MPG, maybe less, but still much better than other cars under the same conditions.
 

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2002 Fuel Economy

I've tracked my mileage and gas comsumtion religiously using an access database for 108k on my 2002 (db file availble for anyone interested). Average is 40 mpg. I drive a lot of freeway miles, living in SF and Sonoma and working full time in San Jose. I've always kept my tire pressure about 32.
 

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Tire pressure too low. Front tires are supposed to be 35, rears 33. See your door jamb sticker. You might do a bit better inflating to 38/36.
 

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My experience has been that the MPG display is most often not accurate. I track my mileage with what's on the display as well as my calculation. The difference can be >10%. I am a cautious driver and with my calculations averate close to 50MPG in the summer. How are you calculating your MPG?
 

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You can't compare calculated MPG of one tank versus MFD MPG, since you can't be certain you're putting the correct amount of gas to reach the same level you started with. Now if you add your tanks together and take an average of your sum, then the beginning/end error will be much smaller than the gallons measured, and will be more accurate.

I found my difference to be about 1.5 MPG, with the MFD being higher. Sometimes though the average difference was more like 2 MPG.
 
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