Something a bit weird has happened after the lower grille block I did 3 weeks ago.
The car's trip computer fuel display was showing me some pretty good results. The first tank showed 6.2 L/100km (38 mpg) in about 60/40 city/hwy driving, but I couldn't confirm it since my step dad took my car for a spin and filled the tank. I didn't want to ask him for the receipt to calculate my actual fuel mileage, but he's a believer of premium gas always and in all cars so I know he put premium inside - about 3/4 of the tank, the other 1/4 being regular. Today I filled up again after driving almost the same 60/40 city/hwy and the car's computer said 6.4 L/100 km (about 36 mpg) but when I calculated the actual consumption based on distance and volume it came to a shocking 8.2 L/100 km (28.7 mpg) - worst mileage since I got the car.
I know there's nothing scientific about any of the above numbers, and there's variability at the pump, but I always fill up at the same station and same pump for consistency and haven't seen that big of the difference between the Honda trip computer and the actual calculated fuel consumption.
Could it be that Honda Fit doesn't like premium gas?