I’ve been noticing that older cars tend to slowly lose fuel efficiency over time, and many owners don’t realize how many small things can cause it. I’m not talking about obvious issues like engine failure, but more subtle stuff that builds up over the years.

From what I’ve seen, the first things to check are basic maintenance items: air filter, spark plugs, fuel injectors, tire pressure, and engine oil quality. A clogged air filter alone can reduce fuel economy more than people expect. Old oxygen sensors are another common cause, especially in cars that are over 10 years old.

I’m asking because a lot of imported cars from Japanese car auctions for Pakistan arrive in good condition, but once they’re driven locally for a few years, fuel average starts dropping and people don’t know why.

I found some useful maintenance and import-related info on https://nobukojapan.com
while researching this topic, especially about auction grade cars and maintenance expectations.

What’s your step-by-step process when diagnosing poor fuel economy in older vehicles? Do you start with scanning tools or basic mechanical checks first?