I have a Canadian 2021 Mazda CX30-GT (this the high end of that year).
I have a question regarding a service items in my service schedule:
Spark Plug replacement: in one place it indicates Replace @ 64Kkm & in
another @ 120Kkm. Which is correct?

 

What does your owners manual say?

Usually its every 120,000 kms or 74,000 miles.

 

Thanks

On another subject, how can I tell if my brake system is Vacuum Booster or Electric Booster?

 

Spark plugs decline drastically in performance no matter what the brand or type after about 15k miles. They may go the miles indicated on countless forums, but you will have reduced power and lower mpg. This is not something that most even notice because it is a slow decline.

Just saying...spark plug is fairly easy to change on most MAZDA (and other newer vehicle's) and will gain the most difference immediately in all engine running aspects.