The IS-F may run mid 12s in perfect conditions and great air, but they're running high 12s, low 13s more times than not. Anytime you see a listed 1/4 mile time for a car that's on a track with good prep, good temp, good da, and an experienced driver.
You see it all the time at the track when guys bring their stock cars expecting to run a time they saw on the Internet only to feel down afterwards. When they don't take all the variables into play.
Stock naturally aspirated cars are affected by weather conditions more than the modded or forced induction ones.