My gas mileage has decreased

Alright here's a related winter question...for those of us who deal with snow/ice, how often do you use the emergency brake (not the regular brakes, but the emergency brake with the handle near the center console)?
Because with Skylis 1 I would get the normal clicks to lock it in place but I just got Skylis 2 and it clicks, just very quietly, and it goes up/down a lot more smoothly like it takes no effort. (The brake light does come on when I pull it up.) I'm wondering if the brake is just froze, since I just remembered now after I let it sit for a night below freezing.
What's the norm?

 

Another related question: How long can I wait before I really should go to a touchless car wash to spray all the salt/mud off the car? I've been visiting for the break, so I haven't used my car much since I brought it home... but it's really cold outside and I have no idea what the effect of these car washes are in subfreezing temps. So, which is worse for the car?? Should I just get all the grime off right away, or is it a really bad idea to do a (touchless automatic) car wash in subfreezing temps??

 

I just had to wash the crud off the "Wintah Cah"... our old trusty plastic bodied Saturn SW2 wagon a couple of days ago. The drive in touchless was frozen shut, so I used the hand sprayer bays. Windows were so mucked up that I couldn't see out... so it was a desperation move... at 6 degrees. The soap froze on the car while I was washing the opposite side, but luckily the rinse water was fairly warm and rinsed the soap off.

Did quickly wipe and dry the door seals to keep the doors from freezing shut. Otherwise, the car and windows came out really clean.

Wash it when it needs it. I'd rather keep the salt off the car as much as possible. Since it's been staying really cold, the car's still really clean. Might want to keep some lock deicer handy if you wash the car in extreme cold temperatures. I don't lock the Saturn, since I really don't think anyone would want to take it. I'm about the only one in the family that will drive it!