[shovel]

I'd like to hear other peoples' thoughts on this... (sorry if it's been discussed, I didn't see it)

Ever since I heard it quoted that the average car, counting classics and counting those wrecked during their test drive, stays on the road about 8 years I've figured that every year you keep a car on the road past 8 you're "recycling" the whole car, effectively preventing it from being scrapped and preventing a new one from having to be built and shipped to your local dealer.

I don't know that the figure of 8 years is accurate, a quick google search brought all sorts of answers from "experts" that varied from 6 to 16, and I didn't see any that seemed to be derived from actual DMV registrations. I know there are regional differences too, life's probably harder for the average Kalamazoo car than the average Fresno car. I'm willing to "buy" 8 years or 10 as a good average. The average car on the road might be older, but that's not directly equivalent to the average car's life span because the ones that died young aren't on the road anymore so you don't see them.

So what do you think? Does it make sense that for every 8 years you keep a car running after the first 8 you've effectively recycled the whole car? If we're to assume that a 40mpg 1985 econocar in good running condition pollutes similarly to a 40mpg 2009 econocar, is there a down side to keeping the old ones on the road?