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Prius Electric Mode Converter

Evidently outside the US, Prii are built with an electric mode switch that the US doesn’t get. Anyone know why? Anyone ever purchase a conversion kit?

I could be wrong, but I believe there is more to it than just a switch. I understand they beef up the batteries as well and maybe include a home charge capability.

It’s true-- there’s a little override switch on non-US Prii that you can push to stop the gas engine from starting. The catch is that in the stock configuration you can’t go very far (<1 mile) or very fast(<25mph), but it’s handy if you’re just going a few blocks and don’t need to warm up the engine. Who knows why they don’t trust US drivers with it-- maybe they figure we’ll forget it’s in EV mode, run out of juice and clog up the Toyota roadside assistance line. Supposedly they were going to start having the EV switch on US Priuses in 2008. I haven’t heard of any related chaos… yet.

There are also conversions out there, like Joseph describes, that “unlock” this feature, as well as put in a beefier battery and a plug, which boosts the batteries-only range and top speed. The conversions are incredibly expensive, though and have mixed results as far as living up to their range and speed claims.

If you buy the EV mode switch (ebay, CoastalETech, etc.) you will have ‘conditional’ access to the EV mode. Installation requires access to somewhat tight space within the dash.

The car will automatically revert to normal mode if the battery gets low, or under some other circumstances. You will not hurt the car by using it. But neither is it going to improve fuel economy, etc.


It has to do with the length of the battery warranty and emission requirements. EV mode may be a little harder on the battery, and doesn’t have much effect on mileage.

I just bought and received the EV Switch from CoastalETech. I have not installed it yet. It looks pretty easy in their picture guidebook. They even threw in some Jelly Bellys with the package. For installation, you just remove the passenger side air conditioner vent, install their $45 switch in the computer circuits and replace the vent. Besides a couple instructions on how to drive using the Cruise Control feature, it looks simple. I’ll let you know when I put it in this weekend.

I currently average 40.2MPG, which is great, but when I bought the car (2007 Prius), I was expecting 50-60MPG and a bigger tax incentive. Hopefully, this will boost MPG at least a little without extra wear on the battery. My brother has a Prius too but he is waiting on my feedback to get an EV switch for his. He drives much more economically than me averaging 45 MPG. Yes, I am a lead foot and if I can save a few tanks of gas at nearly $5 a gallon in San Diego, then the switch is well worth it.

Angela aka PriusGirl

The energy required to move your Prius comes from only one place, the gas tank. Pretending you have an electric car will not improve your gas mileage. Sooner or later the gas engine MUST run to charge the depleted battery…The more you deplete the battery, the harder the gas engine will have to work to re-charge it, resulting in less mileage, not more…

Caddyman is exactly right. In fact, letting the batteries run down beyond where the stock computer usually lets them may result in worse gas mileage, since the motor will just have to run more to recharge them. The only instance where the EV override will save you gas is if you only have to move the car a few blocks or so, where usually the engine would come on automatically to start warming up. You’ll still eventually have to have the gas engine generate the power, but this way you’ll only do one cold start instead of two.

But really, how often do you only drive a few blocks?