Poor gas mileage on 1999 Volkswagen Cabrio

Replaced wires,plugs,cap and rotor
IGet 16.4 mpg from 24mpg

Asked by for the 1999 Volkswagen Cabrio
2 answers 2 comments
Volkswagen parts or aftermarket?
You dont check the ffilter , u just replace , there cheaps.
Try the air + fuel filter ..
How do you check the fuel filter?