By Neil Bravo
Y
ou can never pick the time when fuel prices go up. And just as your pocket start to grimace in pain with the rash of fuel hikes, here comes the dreaded time of the year to use gas—summer.
Gasoline price is almost P60 per liter and there is no indication of any rollback on sight. Now, how do you deal with things like going on a road trip this summer?
Conventional wisdom tells us that first to go would be the aircon. It’s the first to get switched off so we save on gas.
Right?
Eeenk. Wrong.
While we think that opening windows instead of using the AC would save us on gas, we are actually consuming more if we do not know when to switch AC off and open windows.
Close Windows and Use A/C at High Speeds
There is an efficiency debate here: Open the windows in summer to avoid running your energy-intensive air conditioner, or keep the windows closed and the a/c on to preserve your car’s aerodynamic profile?
We came across a very helpful article from Practical Mechanics.
According to Practical Mechanics, driving at 55 mph with the a/c running, yielded a test result of 24 mpg; turning it off resulted to 28 mpg. Then they opened all four windows, one at a time, and lost 1 mpg per window until they were back at 24 mpg. So at that speed, it’s a wash. The reason is that aerodynamic drag rises exponentially with speed-—the faster you go, the more the open windows hurt efficiency.
Now, going back to the fierce debate. Opening windows or switching the a/c on?
The answer: Below 55 mph, open the windows and leave the a/c off. But at 60 mph or higher, keeping them closed and the air conditioning running will burn less fuel.
