Why is my Kia Stonic's fuel economy declining?

I've noticed that my Kia Stonic's fuel economy has been getting worse over time. What could be causing this and how can I improve it?

One possible reason for the declining fuel economy could be clogged air filters. Check and replace them if necessary.

Have you been using the recommended octane level for your fuel? Using a higher or lower octane level can affect your fuel economy.

It's important to keep your tires inflated to the proper pressure. Under-inflated tires can greatly decrease fuel efficiency.

Try to limit your use of air conditioning or heating, as they can also impact fuel economy.

If all else fails, it may be worth getting a diagnostic check done at a mechanic to see if there are any underlying issues causing the decrease in fuel economy.