Rainguards

[Z man]

Do you think they have any measurable affect on drag?

I hope that maybe the air gets pushed outward a little more so it doesn't go inside the cabin as much when the windows are down.

Either way I'm not removing my guards because its nice to have the windows cracked in the rain.

[MetroMPG]

These?


WeatherTech Weather Deflectors shield open windows from wind & rain

The ones I've seen probably hurt a bit - they increase frontal area slightly and Cd. The wost ones are the ones on cars where the rear window guard sweeps down with the roofline, so the open area is facing the air flow.

But as you say, you have to decide what you want to keep on and what to remove. People have different wants, needs & abilities and can't delete every excrescence for the sake of driving that perfect tear drop!

[93Cobra#2771]

I picked up about 1/2 mpg removing mine from circa 1998.

[MetroMPG]

Cobra: give us some context. Picking up 1/2 mpg on a Hummer is waaay different than picking up 1/2 mpg on a Metro!

[93Cobra#2771]

On the escort when it was at about 33 mpg combined. They were older rain guards and stuck out more than modern versions do.

While driving in rain, you could watch water drops come off windshield, roll to side glass and hit rain guards. Drops would come off the guards and get caught in a vortex right behind, or even travel to the front of the car at speed.

Once removed, water now clears easily off the side glass.

One of those little changes that doesn't mean much, but a bunch of those little changes equals a lot.

[aerohead]

That's why Barbie and Ken's hairdo's blow forward when they drive the convertible Corvette.

[Z man]

Damn that's disappointing. Well I like the look and function of them but maybe I should see what improvement I could get by removing them.
I mean, I think I'm getting good numbers in the xB as it is.

[mwpiper]

I was doing an open window test (drive down highway with window open and using hand to sense wind pattern. There is a dead air space to the side of the A post. Air comes off the windshield and detaches leaving about an inch or so of dead air. Consequently, I have the above mentioned vortex all the time. Driving in rain with window closed, water on the side window marks out a pretty clear vortex caused by the air flung out by the windshield.

I'm predict that a) vent visor will not create more drag because it would occupy that dead air space and b) rather than cause a vortex that is already there, it may inhibit it by capturing the airflow that is tucking up underneath it.

Unfortunately, I've been too cheap of late to cough up the $50-$60 to experiment. I'm thinking I might try a cardboard test first.

[MetroMPG]

Most modern cars have aero-unfriendly "A pillar channels" that direct water from the edges of the windshield up to the corners of the roof before releasing it. They likely contribute to the typical A-pillar vortex formation.

The 1995+ Metro does NOT have A pillar channels - instead there's a continuous transition from front glass to A pillar to side glass. Maybe better for aero, but water will stream freely into the car if the side window is cracked open even the slightest amount when it's raining.

Hard to say whether they did this for aero or cost cutting, but I'd bet on "B".

[Z man]

I removed all guards except the front passenger side. It is really easy to remove, they just pop back out. In case it does rain I want to have one window cracked!

It's hard to tell if anything will change since I lack SG.