2004 Toyota Prius FAQ

Gathered from messages posted at the 2004 Prius Yahoo Group: http://autos.groups.yahoo.com/group/2004-prius/

Please email corrections or suggestions for additional questions (with answers!) to the editor: bill.rob@verizon.net

Last updated: 1/7/04

What gas mileage should I expect?
Why is my car only taking 7 or so gallons at the "one flashing bar" stage on the gas gauge?
What is the ICE?
What is the "fuel tank bladder" I keep hearing about?



What gas mileage should I expect?

People who owned the Classic Prius (01-03) report there is a break-in period after which your mileage will likely increase.  Dave Hermance, Toyota's executive engineer for environmental technology, drives an ‘04 Prius and said he typically gets between 53 mpg and 55 mpg combined. But he says he knows exactly how to "pulse drive" the car - that is, to accelerate briskly and get it up to speed, then mostly coast and let the electric motor handle the slight modifications needed to keep the vehicle at speed.  Hermance says the average mileage among Classic drivers is about 44 mpg.  But car makers (including Toyota) are not allowed to publicize anything other than the EPA figures.

A survey of 750 first-generation Prius owners on yahoo.com showed them obtaining between 35 mpg and 55 mpg combined driving, with an average of 44. An early poll of 30 2004 Prius owners showed most got between 45 mpg and 49 mpg.

One devoted Prius owner in Minnesota, http://www.john1701a.com/, says he averaged 45.4 mpg over nearly 60,000 miles in a 2001 Prius. He has since purchased the redesigned 2004 model and has raised his average to 47.1 mpg.  He expects this to increase as the drivetrain continues to break in and warmer weather arrives.

The Environmental Protection Agency has admitted that their reported gas mileage figures are smaller than they appear in the agency’s tests.  For various reasons, the tests produce a mileage figure 15-20% higher than real life.  That’s for all cars, but it may hit hybrid makers hardest. First, since hybrid mileage is high, a 20-percent error is a lot of gas, and second, buyers care. The driver of the average car may not notice if he uses 12 gallons instead of 10 between Reno and Sacramento, while the driver of a hybrid will gripe if he burns three gallons instead of 2.5.

No fix is imminent. It’s been known for years that the tests are inaccurate, but they do provide a basis for comparison.

mpg detractors:


How much gas can I put in when the last bar begins blinking?

As noted on the 2004 Prius list, the gas gauge is better named the "guess gauge". Many people are reporting only getting as little as 7 gallons in the tank at one flashing bar on the gauge, while others have added 11 gallons. This is due to several issues:

Bottom line, the safest thing to do if you do carefully top the tank at each fillup, is to note the mpg for the tank once the last bar starts flashing, and multiply it by 10, to get the maximum total miles before you fill up (9 times in colder weather). This should give you almost 2 gallons left in the tank, which should be enough unless you are in the middle of nowhere. Note, however, that if your end-of-tank mpg is running much lower than the tank average mpg, this rule will not apply, and you should just fill up as soon as possible.


What is the ICE?

The Internal Combustion Engine - the gas engine that indirectly drives the Prius (it cannot directly drive it).


What is the "fuel tank bladder" I keep hearing about?

The tank has a synthetic bladder inside to minimize evaporative emissions (the bladder expands and contracts with the fuel volume, minimizing the air gap over the fuel, which minimizes fuel evaporation, which can escape during filling (or venting in a non-bladder system)). This bladder can become less flexible in cooler weather, which will keep you from fitting a full 11.9 gallons in the tank.






Last modified: Jan 7, 2004
Copyright 2003-4, Bill Robbins, Tom Stangl, Michelle Vadeboncoeur
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