Q: Fuel economy getting worse on a 2000 Opel Astra G

You generally get bad fuel mileage for either the air filter that is clogged or the MAF sensor that measures how much fuel goes in to see if either is dirty or needs to be replaced. Fuel injectors could be dirty. Watch my video "how to clean fuel injectors on your car." There are a a lot of things that can make cars get bad fuel economy but you’d want to check all of those things first. Now, it is a 2000, so you can have a data stream. Have a good mechanic plug in a scan tool and check the data stream. See if the sensor is working and see how the fuel injectors are firing. A mechanic can get a lot of information from the car’s data itself. If you’d like, a technician from YourMechanic can inspect your car to see how you can address any issues that may be causing poor fuel economy.