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From Los Angeles Times, 18th February :

Toyota Prius software fix may reduce fuel efficiency, experts say (at )

Interesting story about Drive Train Heating, and a Software correction to counter that problem brings about some difficult times for owners and for Toyota .

We've had discussions here on Allpar regarding Quality, Reliability, and related. We also extended those discussions to include Dealership activities as well as noting how Corporate responds and how they treat the Customer.

The following is taken from the article ( 'the company' is Toyota ) :

The company's documents show it modified not only software that controls the inverter's function, but also the software in the vehicle's powertrain control computer that determines how much power is supplied to the transmission by the gasoline engine and by the electric motors, according to the experts, hybrid vehicle engineers at major academic research centers.

The inverter, a device about the size of a large shoe box, boosts the battery's 200 volts to about 500 volts for the electric motors and converts the battery's direct current to alternating current (similar to what comes out of a household outlet). When the brakes are applied, the power flows in the other direction to charge the battery.

The change in the powertrain software and evidence of physical problems in the inverter probably shows that the company's modification reduced the power supplied by the battery and increased reliance on the Prius' four-cylinder gasoline engine, according to the academic experts who have reviewed those filings. If so, the car's fuel economy probably dropped and its emissions increased, they say.

The Prius has an EPA fuel economy rating of 51 miles per gallon in city driving for the 2010 model and 49 mpg for the 2014 model. Enger said his city driving mileage dropped from 49 mpg before the software change to 44 mpg afterward.

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Interesting detail.


Super Moderator
37,232 Posts
See, no company is immune to glitches. This one sounds like it will upset companies and the EPA.
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