Rain, rain, go away!

[AeroModder]

A note on wet-weather driving: If the road you're on has ruts from tires rolling on it constantly, drive on the higher parts out of the ruts. The ruts will fill with water, so you'll be driving through puddles constantly. You may have to drive closer to the lane next to you, but you'll be getting less rolling resistance from pushing water out of the way and driving on a smoother surface.

[wmjinman]

Wow, it took a while to find this thread, but I wanted to find an existing one vs. starting a new one if possible. I went out to the next town today and it was raining pretty constantly (fortunately, not too common here). And while I was accustomed to my mileage increasing and increasing as the miles ticked off, I was having a helluva time getting the darned "today" average on the ScanGauge up to 21.

But the road was pretty wet, and although I instinctively tried to stay out of as much of the standing water as I could, I know I was driving mostly through water, anyway. So my question is: how much will a wet road cut your mileage? I would say it was at least "several" MPG for me ..... 21-ish vs. the 26-ish I'd grown accustomed to. I had a passenger this time too, so a couple hundred pounds more weight. Dunno if that effected it other than accelerating & going up hill. ???

[wmjinman]

A second question I forgot to put in that last post: Will operating windshield wipers add enough drag to reduce MPG? I've read the threads saying that in the "off" position, they're in a "high pressure pocket" where the relative wind doesn't really interact. But when operating, they spend a portion of their time "up" on the windshield. Just wondering how much that's worth? Probably far less than the mirrors being in the "normal" position or "folded back", I imagine. Any thoughts/knowledge?

[Gealii]

Originally Posted by wmjinman

A second question I forgot to put in that last post: Will operating windshield wipers add enough drag to reduce MPG? I've read the threads saying that in the "off" position, they're in a "high pressure pocket" where the relative wind doesn't really interact. But when operating, they spend a portion of their time "up" on the windshield. Just wondering how much that's worth? Probably far less than the mirrors being in the "normal" position or "folded back", I imagine. Any thoughts/knowledge?

using wipers will reduce mpg when in use the air is catching on them and now you have a higher electrical load to use them. And one thing not all wipers are in an air pocket, take a leaf and place it under the wiper if you see the leaf moving extremely then air is dragging on the wipers

[wmjinman]

Thank you, Gealii. Another thing to test - I love it!!! And this is a handy time of year to find just the right leaf!! LOL.

You know, when I got up this morning, I thought DUH!! - when a car drives on a wet road, there is a tremendous amount of spray that comes up. (I know this too well from being a surveyor standing alongside the road and witnessing this many wet times) But if you apply a little "obvious" physics, it takes energy to pump all that water into that spray - and the energy comes from the car - - energy that probably would be pumping water if there was no water, huh?

[user removed]

If you want it to not rain just throw out some grass seed. Works like a charm for me.

regards
Mech

[Mustang Dave]

Originally Posted by Old Mechanic

If you want it to not rain just throw out some grass seed. Works like a charm for me.

regards
Mech

And if you WANT it to rain, wash your car. works most of the time here.

[Gealii]

Originally Posted by Mustang Dave

And if you WANT it to rain, wash your car. works most of the time here.

me and 2 friends just washed our cars so ill get back to you on that theory

[brucepick]

Don't blame it all on the water. Blame a lot of it on your increased need/want for electricity and a/c for defrost.

This past summer I did an alternator delete with two substantial deep cycle batteries to provide for all the electrical, and also an ac compressor belt delete (after the compressor seized up).

Now I don't get nearly as much of an mpg hit in rain as I used to. Yes I run down the batteries faster running headlights and fan and wipers, but fuel economy doesn't drop as badly as it used to. All that electricity and of course the a/c for defrost used to run off the engine. No more!

Having done those deletes, I can say from experience that a lot of the mpg hit due to rain is from the accessories we want to run in the rain.

[user removed]

Originally Posted by Mustang Dave

And if you WANT it to rain, wash your car. works most of the time here.

I washed both cars today. It was less work than chasing the birds away that were eating the freaking grass seed. Of course I could have just put my crabby wife out on the porch and the birds would have left the country.

regards
Mech