Does cold weather mileage change on non-hybrids?

Yes, all vehicles will be realizing lower mpg in cold weather. The gasoline engine is less efficient in cold weather. As you use the heater, that takes energy that would otherwise keep the engine warm.

However most cars don't have an average fuel economy gauge staring in your face all the time, so it is not obvious that your mpg has decreased.

Your mpg decreased 10%, from 52 to 47 (which is still remarkable, IMO.) If a regular car at 20 mpg showed a 10% decrease, it would be down to 18 mpg which is not noticeable unless you track your gasoline purchases and odometer readings.

 

"Are non-hybrid vehicles also getting lower mileage with all this cold air?"

Is the Pope Catholic?
Do bears have fur?

It has been ranging from -20 to +5 here, and my other vehicle has gone from 22mpg to 16.

 

Absolutely. It was one of the first things I noticed when after starting keeping fuel logs decades ago.

In addition to what Patrick mentioned, winter gasoline blends normally have lower energy density than summer blends. And colder air is more dense, causing more air drag on the highway, and reduced efficiency in throttle-controlled engines. The later is more significant in traditional Otto-cycle engines (fixed valve timing) than in the Atkinson-cycle engines (variable valve timing) found in today's good hybrids.

 

Of course it does... but most people are totally unaware.

Having a display that so readily make that data available is very much a mixed blessing. That information can be empowering and at the same time disheartening. I've got spreadsheets from the early 90's (download xls, note the tabs at the bottom) that clearly show my '84 Omni affected by the seasons.

The cycle of MPG up's & down's is nothing new. But when gas was cheap, few cared. Even now, some are still enjoying the bliss of ignorance.
.

 

I can answere this

92' Ford Bronco FullSize with 302/auto
mod for higher mpg (factory 10/14, now 16/22)
Towing a 3500lbs trailer 600miles at 65mph i was getting 14mpg temp around 80F

This week
Temp around 0F
10mpg
also been using the 4x4 system due to 20+inches of snow we have recieved since 12/24/09

I would have to say YES cold does matter.

Im really missing my prius now, ill take 32mpg during these cold days then 10mph
My ford heater system sucks takes forever to warm up the cabin.

 

Having the fuel economy display really calls your attention to how it is affected by temperature/season. When I was driving my 1996 Corolla, I only noticed it because I kept a record of my fuel economy. Looking back at my fuel records for the Corolla, it looks like I typically was in the lower 30mpg range most of the year, but dropped into the mid-upper 20s in the winter. Can't wait for this cold weather to finish. I have dropped from 55mpg to 41mpg in these single-digit temperatures. I'm eager to find out how much my new tires will affect my fuel economy, but it's hard to do a good comparison due to the impact of the cold weather.