What causes poor mileage on a 1990 Volvo 240?

Poor mileage on a 1990 Volvo 240 can be attributed to several factors, including a faulty oxygen sensor, clogged fuel injectors, or a malfunctioning mass airflow sensor. Additionally, issues such as worn spark plugs, low tire pressure, or an improperly functioning air filter can also contribute to decreased fuel efficiency. Regular maintenance and timely replacements of these components are essential to optimize fuel economy. Lastly, driving habits and load weight can further impact mileage.