Car has 80,000 on it and I've had the car for 10,000 and just decided to look at the plugs. They are Volvo brand. Not sure how long they've been in there but I removed just one and it was very stuck - but did come out. So... does my computer expect a plug like the one I have removed. Would another brand with perhaps a different burn characteristic cause the various sensors to freak out. Or no big deal? That said, I'd rather just put in cheapo plugs if expensive plugs are just hype. So, any ideas? When I read about more expensive plugs they claim the spark is longer, etc., and so I wonder how that would indeed effect combustion.