I have a 2004 DC 4x4 taco. I bought it in july. I use to get 18-20 mpg on regular fuel all summer long. I even got 22mpg on a trip up north in mich in the summer. Now I get 15-15.5 mpg. I drive 60% city and 40% highway most of the time. The only mods my truck has are in july I installed a Truxedo Tonneu cover and a drop in K&N replacement air filter. Is the winter gas blend just shitty that the stations sell? I only use BP regular grade fuel (87 oct). Any opinions or suggestions out there that could help me. By the way I check my tire pressure weekly and I keep it at 32 psi, even when it is 5 degrees Farenheit here in Detroit.