Our first tank... I got 250 miles before we hit the 3/4 full mark. This latest tank... I have 140 miles and I'm dipping below the 3/4 full mark.

The first tank we filled up with high octane gasoline. This last tank we filled up with regular... but I was told the Altima hybrid didn't need high octane.

The electronic guage reads 35.5 mpg... which is the same reading it was giving us before when we got 38 mpg off the tank.

Any theories?