A good practice is to replace your spark plugs at 60,000km interval to prevent misfiring to the engine combustion. The benefits of spark plugs help to regulate and ensure optimal combustion - affecting important factors such as fuel economy, smoother starts and acceleration.
If your fuel economy starts to suffer or your car is misfiring, it could be due to your spark plugs and may be an early sign to replace them. This may also be a sign if you find your car hard to start. The good news is that spark plugs tend to have a long life span of around 100,000 miles so replacing them isn’t a regular affair.