06 Civic costs oil, what's the matter?

This is the first time I've heard about your problem! If it is 13.7 km, it is very problematic.

Civic is famous for its fuel economy. If the high-speed running (here refers to the speed of 100- 120) is not within 8 liters.

There is something wrong with that car! Even if the city runs at a high point, 13.7 does not rise.

Unless you drive it like a racing car.

. Idle jitter is simple.

Go to the service station to clean the throttle and idle motor.

If not, check the circuit. also

Is there anything wrong with your method of measuring fuel consumption?