This is odd… but hopefully someone can have some insight into this.

While on my trip to NJ from Southern MD, which is about 350ish miles on the trip. Well I filled up in MD on the first take I had about ~17 mpg, on the second take (6 gallons of MD gas and 11 of NJ) I had about ~18.5 mpg. Well here is when it gets weird, on probably about 99% NJ gas I was getting ~22 mph.

Going up was steady with cruise set at 70-75 mph… Now coming home I was going with the flow of traffic for 100 miles (65-80mph) then anther 100 miles at 70-75 mph.

So why did I get better miles per gallon in traffic, which was traveling faster for longer periods of times. The difference is 5 mpg with a harder driving style, so that makes me wonder a lot.

Does my gas in Southern Maryland SUCK?

 

most likely it's because of the different amount of ethanol (or other oxygenator) in the gas. ethanol as about 10% less energy per unit mass so you typically get worse milage with oxygenated gas. i know that when the stations around here switch from winter to summer blend my milage goes from about 22 to about 25. and out here in colorado, the counties that are up in the mountains and don't have to worry about the smog and stuff like denver does, don't have (as much) oxygenated gas, so if i drive up into the mountains to get gas i get better milage (really i still only get about 24 mpg or such, but that's because i'm in the mountains and i'm running full throttle on my 22re all the time - but i do notice much more power with gas from the mountains). so after all that rambling, i'm going to assume that maryland runs higher ethanol content gasoline than new jersey does.

 

could it be you did all highway, I know on the highway I hit 20-22mpg but in the city with my lead foot I dipped as low as 13mpg.

did you switch octane or brands, maybe towards NJ is slanted down but going back is slanted up

 

 

also what about altitude, and vehicle temp? a warm vehicle will get differnt readings than a cold vehicle operated in the exact same intervals/speed..... altitiude will cause the same effects

 

Temps where about the same, BUT the humidity was lower on the way home. I don't think there is that much differences in Altitude.