Cold weather DOES play a role in this issue.

The colder weather is the demand for fuel is greater,especially when the VX has rest for several hours the fuel-air mixter during the engine pre-heat increases fuel use.

I noticed the increase in fuel use during these last 2-3 months,mostly when the temperture goes under 40~ i run the engine for no less then 10 minutes,during the first 5 minutes or so the high RPM can't accurately tell how much fuel were consumed during that short period of time until it goes down to normal but certainly is a good amount