My Honda Insight is a 2005 purchased new. After only 1800 miles ...
(2 weeks, average drive 120 mile round trip) Honda diagnosed my EGR valve problem as really being debri in the EGR port.Solution was to replace the head.
Head was repalced but the car is not nearly as quiet as it was 6 weeks earlier when I bought my Insight new (Honda had it for a month waiting for the head, I drove a rental car 2005 Civic 30 mpg average)
The mpg is still great, average 70+mpg.
The pep in acceleration is a little bit less, slight.
The noise is what I notice most, brrruummm instead of hummmrooom and when idling the motor is just not quiet anymore (the most noticable)
Arrgghhh... I wish I could just start over but I know there is a lot to learn here about a great car!