Windows open vs fan only vs climate control

Studies have been done.......but not recently.

The findings were:
Opening the windows was NOT more fuel efficient because it increased the wind drag so much.

I am assuming that if all you need to do is offset the heating of the sun on an otherwise cool day, that a combination of fan-only and cracking a window or two would be a bit better than running the A/C. But then again, under those conditions the A/C wouldn't be using much power either.

I personally refuse to dwell on insignificant stuff like this.
I leave the climate control on AUTO and don't worry about it.

 

more importantly, if you are warm, so is your battery.

 

You got a Prime, man! Just drive it. Stop fooling around with all those theories and enjoy that new car.

Windows down? Yeah, sure. Then you will be back here complaining about all the dust and dirt on the big black screen.

 

Good attitude.

 

windows open up to 35 mph, closed with fan as long as you can stand it, then a/c.

 

In SoCal where "nice days" are the norm, by default I drive with the windows a couple inches down on the other side of the car. If it's a really nice day, I might roll down my driver's side window all the way for a little bit, but my default is usually keeping mine closed, but rolling down a bit the two windows on the other side of the car.

I personally don't like aircon unless it's really hot or humid. Yes, there are times to use it, but while I know most people use it (or set a climate temp and close their windows) by default, I'd rather just open the windows a bit and get normal air (unless you're behind a polluting truck or something).

Having an open window would cause, at most, just a slight decrease of MPG -- certainly it's much better than having the aircon on. Just having the "fan" on might be ok, but for some reason I've never liked the quality of the air that comes through the vent when it's just the fan (regardless if it's set to recirculating or incoming air).

 

keep doing what you're doing and the Prime will surprise you ...

I drive with my right-side windows slightly cracked til ~80F, then AC ... battery doesn't like it too hot either ...

 

The best option if you have the extra $$$ is to spring for the (much) more expensive ceramic tints which will keep your car cooler in all 3 scenarios! Well, maybe not if your windows are all the way down but who does that?

If you feel like risking it, tinting the windshield will greatly add to the heat reduction also.

 

Summer, we rarely if ever use AC and windows up. Just control temps with windows: rolled right down at low speed, progressively rolled up at higher speeds, open just an inch or two on highway. Easy.

Someone will be along shortly to say how it never gets warm in the Pacific Northwest. Maybe not suffering hot, but it has been a hot (and dry) summer for us.

 

You mean it's not true that people in Washington and BC drive with their windshield washers on nonstop during the summer, just so they have a feeling of normality?

 

AC off, all windows down for the first couple of minutes. After that, all windows up, AC on auto and Eco with s-flow. Fan only with window down just blows hot air on you. That only works if it's cool outside.

 

If wind is enough I use the fan;
otherwise A/C

Either way the windows are closed
The exception might be in the cabin interior has heated up after a long park. Then I drive with windows open for a couple of minutes. That is an usual case for me because I seek out shade or use the windshield sunshield with the windows cracked open.

 

I believe that is an old rule, for traditional cars and their traditional inefficient AC systems.

In 2009, the Gen3 Prius introduced a new kind of expansion valve system, taking a significant step forward in automotive AC efficiency (previously used only in non-mobile systems). This stacked atop whatever gains the earlier generations made. So the windows-vs-AC crossover speed should now be lower.

 

could very well be.

 

I agree with that 100%.
Here in Houston there is no option of driving without A/C, but first couple of slow miles with windows down and no AC to bring the interior tem to ambient one makes significant EV range impact.

 

I've still yet to consistently break 40 EV range.

But yes, with windows open it's less efficient, I'd say at 35MPH+.

One other factor that seems to make a big difference is running your HV mode uphill. It seems on flats or small up-grades EV is more efficient overall.

I have a 50 mile trip and I try to bank my EV until the end, and/or get high MPG in the beginning and up the hills. The Efficiency Coach seems to evolve on how you drive and gives you the best economy. It seems to remember when I slow down right before the top of the hill before I glide down.

But...still waiting for my 40 EV range hah.

 

Mythbusters did a show on this and on their limited test they did, the windows out performed the AC (gas mileage wise) at a steady 45mph: AC vs Windows | MythBusters | Discovery