A little background info first. My commute to work every day is very regular. Always the same traffic conditions, the same idiots that interrupt my P&G or tailgate me at the same spots. And today was just like any other day has been, Even if it was a little (10-20 degrees) colder than the past few weeks. Anyways, i get to the point where my first 5-minute bar shows up (stopped at a certain red light waiting to turn left). Normally, it's somewhere in the 30's - It's about a mile from my driveway, and between warm up and accelerating to 40 (speed limit on one road), i can't get great mileage there. However, today it showed 100MPG. So obviously when i see that i get a little worried... did something go wrong with the computer? A little bit later, my next 5-minute segment shows up. This one's normally around 75, and i'm happy to see that it still is. My third (and final) 5 minute bar then shows up. This one's usually down around 50 - a lot more stop signs in this portion of the commute, plus some pretty decent uphill runs. But no, this time it's around 80. I want to stress that there was absolutely nothing different with this commute than the previous few months. The traffic patterns were exactly the same. The total time of the commute and time spent at lights and stop signs was exactly the same. Anyways, it's just bugging me.
That first segment seems odd. I've envied those with engine block heaters who have first segments up near 50 but I've never heard of a morning drive with a first segment at 100. Well, a normal 40 MPH in traffic one, that is. You said 10 - 20 degrees cooler. Weather.com is currently showing St. Paul at 65ºF. For me, that's about perfect for a long commute since I can use the vent without getting too hot. But the overnight was 56ºF and without a heat source that's where you engine would have been.
you need to immediately deflate your tires to below the numbers on the door, overfill your oil to above the "max" mark, you should start driving more aggressively and braking late and exceeding the speed limit so that, with some effort, you can get those mpg numbers back down where they should be. Good luck and stick with it! Ok, sorry. May be just a one-time quirk, wouldn't worry right now, but keep an eye on things. Hard to give any specific advice at this point.
Yeah, it's been up in the 80's and 90's here the past week or two (93 on tuesday when i was playing softball!), so it's definitely cooler. And like you guys said, it's odd but not really something to rush to the dealer for... it's just bothering me and i feel like i'm being paranoid.