I first bought my '07 Prius on the last day of 2006 (just in time for my tax break). Since it was the middle of winter I was getting around 38 MPG, and in the last 7 months it has increased to around the 47 MPG mark. Most of my trips are less than 3 miles, which includes a steep 300ft elevation change. Yes, hardly ideal conditions for any car. After a week of owning my car I installed the Radio Shack EV mod so that I can force the engine off for these short trips (since there's no chance of the engine warming up anyway). However, I've been using the same technique for longer trips around town. I'm probably keeping my engine in stage 3 for longer than if I let it warm up on its own, but I've convinced myself that I'm getting better gas mileage this way. If the car warms up to Stage 4 I Pulse & Glide normally. I would install a block heater, but I live in an apartment. I try to keep my battery at 5 bars or above by accelerating so that no arrows are going to or from the battery. First Question: Does this technique make sense for my short trips? Second Question: Does this technique make sense for my longer trips while my car is still in Stage 3 (do hyper-milers ever do this), or should I let it warm up to Stage 4? Third Question: I've read that using the EV mode improperly can keep the catalytic converter inefficient and increase certain types of emissions. But if I'm using less gas, then is it possible that the overall emissions per trip are smaller?
Using the EV button to mimic stage 4 while still in stage 3 is a proven and effective method of improving mileage. It won't do any harm to emissions as long as you restrict your ICE off times to what the car would normally allow, which is no more than a couple minutes. (Remember that stage 3 and stage 4 are identical as far as the engine is concerned...you're fully warmed-up. Stage 4 is just what you get after you've let the car go through its 5-10 second "idle check" thing while at a complete stop.) Just resist the temptation to dip into that battery for propulsion! Now, Stage 2 EV button pushing might be different situation. Again, you will definitely improve mileage but emissions may be at risk since the car is still trying to get warmed up at that point. Unfortunately the only way to tell is with additional instrumentation to check coolant temp or break 35mph and see if the ICE shuts itself off during a glide. It's up to you, I guess. I suspect that S2 EV-ing may impact tailpipe emissions but I can't prove it.
I have on occasions over extended the EV distance and drained my battery to three - or even two - bars. This is bad. Bad. BAD!! And oh do I pay for it. For the next long time, the engine is running to recharge, mileage absolutely sucks, and I am hating life. So while, like brick said, you can use it wisely to improve mileage. The key is responsible and judicious usage.
I might as well ask here. Is there an EV button I can install on a 2002 model? I've only seen buttons for the 2004 and newer models.
<div class='quotetop'>QUOTE(TonyPSchaefer @ Jul 11 2007, 09:26 PM) [snapback]477224[/snapback]</div> The Prius is a gasoline car. There is no free energy. The battery going down to three or even two bars on the MFD isn't bad, bad, bad. It's normal. The software will take care or making sure the batteries don't go beyond the programmed limits, high *or* low charge. It's not bad. But as you say (since there's no free energy), the engine WILL run to make up for it all. The EV switch doesn't turn the car into an electric vehicle. There ain't no such thing as a free lunch.
<div class='quotetop'>QUOTE(chuck_k @ Jul 12 2007, 05:12 AM) [snapback]477400[/snapback]</div> That's why he said it's "Bad bad bad." Not because it will hurt the car but because it will tank your mileage due to all of the conversion losses while sending energy back and forth from engine to battery to wheels.
<div class='quotetop'>QUOTE(brick @ Jul 12 2007, 10:11 AM) [snapback]477219[/snapback]</div> The Stage 2 behaves as same as Stage 4. Are you saying about Stage 1b or Stage 3? Ken@Japan
<div class='quotetop'>QUOTE(Alexstarfire @ Jul 11 2007, 09:57 PM) [snapback]477345[/snapback]</div> Assuming the connection (and the software) is the same, you can install your own button, like the OP did.
<div class='quotetop'>QUOTE(aaf709 @ Jul 13 2007, 12:05 PM) [snapback]477900[/snapback]</div> They are different animals. The hybrid ECU of 2004-2007 Prius has the EV button function, but there are just lack of button and cables on the 2004-2007 NA model. Ken@Japan
To avoid being an "EV Button Pusher", figure out how to modify the voice commands software. Maybe it has a spare output that could be used to connect to EV circuit, and you could just say "EV Mode".
