G Force chip

Those who examined the chip claim it is altering the reading of the temperature of the intake air, in an attempt to fool the computers into thinking it is warmed up.

Certainly the Prius drives differently when warm, but remember it is not actually warmed up, the chip is just lieing to the computers.

If the lie were innocent, the Prius would only have more HP and MPG when cold, as when warm it would do no good to lie.

In fact, the reason the Computers want to know when the engine is cold is to get bet better emissions, so the chip will cause you to pollute more when cold. And since the computers think the engine is warm, it will stay cold longer, since the computers think they are done warming it up.

So after the first 15 minutes, it has no effect, but for the first 15 minutes each day you are polluting more in the hopes of better MPG.

Clearly I dislike that idea, only you can decide if you dislike it as well.

Buying a Engine block heater costs about the same and REALLY warms the engine without lieing, so has no pollution downside but is documented to get better MPG.
PriusChat Shop : Toyota Prius Engine Block Heater [Prius EBH] - $59.00