How seat warmers affect MPG

Alright, I'm not too sure what happened yesterday. I made my usual commute from Plymouth Meeting, PA to South Philly via 50% hilly backroads and 50% highway. The hilly backroads usually get me about 56mpg in warmer weather. The highway portion/driving in the city gets me about 54-58mpg. This was only observed for a few weeks before the weather got cold/below 55.

New tank: Yesterday, I achieved 69mpg over the same ~20 mile commute of 50% backroads and 50% highway/city. The weather conditions were sunny and mid-60's. My 7 mile return home that night at 55 degrees showed 67mpg for the tank. The traffic on the backroads was really crappy and I ended up having to run the engine at least once to regen battery (nothing I could do about that).

The differences I can find, since my driving habits did not change and I wasn't even looking at my real time MPG until I got to the halfway point: tire pressure was at stock in October/November. I adjusted to 44/42psi in January. I don't know what they're at now. Seat warmers were off.

This morning, I had to drive my usual uphill highway commute to work. Temperature was about 40 degrees (f). My MPG after 12 miles for the overall tank was in the low 60's still; a drop of about 4.5-5mpg. I didn't use the seat warmer again.

I can't imagine the seat warmers playing such a role in my gas mileage. Could I have gotten a better fuel formulation? I got gas from a Lukoil station yesterday instead of my local Sunoco. I also imagine my tires and engine weren't broken in back in October/November when I was under 2000 miles for the tank.

Still, I saw a pretty abrupt 20% increase in MPG and my commute was really no different, if not worse than normal. Any suggestions so I can try to maintain this? I'm suspecting it's a combination mainly of different gas, ideal ambient temps, engine break-in, and higher psu when comparing to my fall tanks; as opposed to any sort of savings from not using the seat warmer which I cannot fathom makes any more difference than using my headlights.

 

Germantown to Ridge to Umbria. I try to stay off Ridge for as long as possible. Plus, Umbria has no lights and is a pulse/gliders dream (aside from the tailgating haha).

The 67mpg came from driving from South Philadelphia to Bala Cynwyd, so not quite as far as the initial commute of Plymouth Meeting to South Philly. And the 57mpg is actually pretty high considering what I average in lower temperatures (40 degrees when I left this morning).

I thought it could've been because of my low average speed, but I'm generally in the low 20's due to the rush hour traffic on Germantown/Ridge going home everyday (I take 76/476 in the morning).

 

I go with EV once the stop signs start at the train station now. I only lose one bar at the worst and I'm generally topped off anyway from the ride down Shawmont. Shawmont's also 50% of the reason why I take 76 in the morning haha.

Yeah, I definitely wouldn't touch 76 going in the direction you are. I've never seen it not backed up for miles going East in the morning and West at night. Kelly to Henry to Ridge West are always clear during the evening rush. It's pretty amazing, actually.

By the way, what sort of mileage are you getting? My 2008 generally got in the mid-50's in good weather. Sometimes up to 55-57 for a tank, if I can remember correctly.

 

I hardly ever use the heat. Spins the engine too much to get into my comfort zone so I just wear gloves and a hat if I don't have passengers haha.

 

My commute home was terrible today. I'm down to 58. For some reason the ENTIRE commute the engine wouldn't stop. I just couldn't glide or even go on battery. Friggin terrible.

Mornings: Bala Cynwyd to Plymouth Meeting
Evenings: Plymouth Meeting to Bala Cynwyd or South Philadelphia