Snow....what an impact on MPG

Were the roads clear? I'd think snow on the road's going to impact rolling resistance, even wet roads make a difference.

It's best to brush snow off the roof, avoid it blowing off, blinding someone following you. Also, do take it easy: 60 mph in snow is freaky.

BTW, I was out mowing the other day.

 

That's pretty extreme.

Conditions permitting, I try to sweep as much off the car as possible when I'm setting out. I've seen mid 30's under similar conditions, with my hatchback.

 

yes, the road friction is brutal on wet/slushy streets.

 

The hard data I found in this was a Missouri road surface roughness pre-post study that found very small 1-2% differences using dump trucks as the test vehicles.
BUT, anecdotally I have had big reductions in mpg due to rough, rutted, potholed gravel roads, which I attributed to increased rolling resistance (from 55 to high 40s, so more like a 10% or more decrease). Anyone else have data for gravel/dirt road mpg changes ??

 

I agree. The last two winters here in Michigan have been pretty damn snowy. What I do to circumvent the huge mpg drops in the winter & plowing through the snow, I installed an engine block heater and I grill block 100%. If the wheelwells are caked with snow kicked up from the road, I stop at the $.25 car wash and get it out of there, as well as anywhere else on the Prius. I then go home, park the car in the garage and start out the next day fresh!

 

Snow on car: 10% of your drop in MPG.
Cold temps: 90%.

 

Ice on your roof is as dangerous if not more dangerous than blowing snow! Every year there are deaths on the highway attributed to chunks of ice flying off of vehicles causing a wreck, either directly or indirectly.

Def. Take the time to carefully break that ice off before you start on your trip pls.

Yes the cold weather really kills our MPG. It sucks but what you can do is slow down, try 55mph as in bad weather you prob shouldn't be driving much faster than that anyways. Block your grill, pump your tires up a bit. I run 44/42 but that's a little high for most, try 40/38 for starters.

Watch some YouTube vids on how to drive the prius for optimal mpg. Bob Nagy comes to mind. Learn to pulse and glide. Don't warm your car up for too long if at all if you can hack the cold. The higher you set your heater, the longer the gas engine will run and won't shut down thus burning more fuel...

All the best.

 

Oh and was that 24 mpg just for a short trip, for a longer extended highway drive, or for an entire tank?

If it was just for a short trip it's nothing to worry about as the car never got up to temp.... When I make a quick few Minuit run run to town and back I can even score worse for mpg, goes for all of us in a cold climate with a prius.

I don't think 24 mpg is even possible for an entire tank even driving one like a race car. Lol.

Ok Sir, we are simply trying to help! In my last couple posts I gave you every tip I know to optimize mpg...

Obviously my statement in reference to the icy/snow on your roof was a friendly (legal) reminder. Sorry for "scolding" you.. I'm quite sure most people that caused accidents by way of ice / snow flying off thier roof were "sure" that it was not going to fly off thier roof...

Either way best of luck with your v. If you do everything I stated in my last post and still get 24mpg consistently maybe the dealership upsold you on the new Hellcat v?

 

Your own incorrect assumption was that the snow/ice stuck to the car had much to do with your low MPG.

 

Don't underestimate the value of the aerodynamics of these vehicles (and the drag from having irregular snow on the roof)--I'm agreeing with G Man v5.

You'll notice that the v takes a hit in highway mileage relative to the hatchback. A good part of that is the difference in its aerodynamic drag.

 

So I suggested removing the snow and ice and you considered that "scolding". Lol.

And removing the snow and ice totally solved your problem.

We "chimed"in because you started a thread asking a question...

-your welcome.

 

Years ago I had a windshield taken out from ice/snow blowing off the cab of an 18 wheeler coming towards me on a 2 lane road. Entire windshield honeycombed with cracks. Since I was only 4 miles from the ski resort, we went skiing as intended, then drove back home with my head hanging out the window or crouched down peering through the 4 inch undamaged portion of the windshield corner while a passenger watched the side of the road. Scary.

It isn't just the top of the car that gets inefficient in passing air, look at the sides of the car and see the accumulation of snow build up there that creates a rough surface.

And even on a wet surface, your tire is pushing at that water and MPG suffers. Worse in snow.

 

Lets not forget, that the little 1" air deflectors underneath the car, near the rear tires, affect Mpgs. There were a few members here that removed them and their mileage dropped!

The Prius is very sensitive to factors that affect aerodynamics. Absolutely snow all over the car and in the wheelwells, or underneath the car do not allow the air to flow "smoothly".

 

It seems to me you drive down the road, you have your heater on. The metal on the top eventually gets slightly warm and then melts the underneath of the icy snow just enough to break the bond between the ice and the paint finish. The car hits a bump. The stuff is now able to break loose and air is pushing up and against it and it flies off. How does this not happen? And the faster you are driving, the more air is pushing against that stuff and the further it is going to fly and it doesn't necessarily stay in your lane as my experience cited above taught me.

Thanks for posting your experience. I had not thought of the effects of some snow accumulation on the surface of the car affecting mileage until you posted.