Your mileage may vary; ours has

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My life with cars has been driven by a combination of bonehead purchases, lazy stewardship, and just plain bad luck. I've tried to improve with age, but I still feel snake-bitten. (The next-to-last car I bought was a VW Passat, based on the strong recommendation of Consumer Reports, but the car was an unreliable, high-cost, high-maintenance disappointment.)

Which brings me to our Prius, which we purchased about 22 months ago. I'm writing from our dealership, where I've come to try to learn why its mileage performance has substantially declined. I've just had my consult, and the news is not good. That is, there is no news, no mechanical flaw.

We started off in the high 40s when we purchased in June '06, and occasionally topped 50 for a tankful. In our first winter, we migrated to the lower 40s, not pleasing but standard, apparently, for colder climes. (To produce heat, the engine has to run; it's always running in a gas-only vehicle, but not in a gas-electric hybrid, so sometimes, wits engine runs only to warm the passenger compartment.)

In our second summer, mileage rebounded, not to the best numbers of the first year, but still great compared to guzzlers and good by any measure. Last fall, mileage again fell with the rise of the cold, but far worse than the first cycle: Between Nov. 22 and Jan. 7, the range (as recorded in a handheld app I have for the purpose) was 30.5 mpg to 38.1, and even here in early April, the dashboard monitor says we're getting 40.1.

I called the service department over the winter, asking for help, but was told that our experience was normal — even after I made clear it wasn't normal compared with our first year's performance. Yes, I know it worsens with cold, I told him, but I'm talking about the decline in the range, not the rate. But he wouldn't budge, and what was I going to do? Their position was that there was nothing to investigate. 

I even called a Prius press rep., asking if this second-year drop in the warm-cold MPG range was to be expected; his response, essentially, was to suggest that we look to the operators, not the machine. And how was I going to refute it?

But I've continued to see bad numbers, so I called the dealership again this week, and though I still felt they regarded the request as sky-is-falling blather, I insisted this time. 

The report was as they expected — don't see no problem here. "Could be the way you're driving — city or highway, of what you're carrying, or something else. But the car hasn't changed," the service rep. told me.  That will be a hundred bucks, please.

I asked to speak with a manager, not to complain but to seek a comment for this post. The guy not only declined to comment for the record, he objected when I told him I would report that the dealership had declined to comment. (He also urged me not to use the names of any of the people I spoke with, or the name of the dealership; two outa three ain't bad, but then again, it certainly isn't about individuals and really isn't about the dealership either, even if they're not the warmest organization I've ever dealt with.) 

The second guy said I could take my case to the next level within Toyota, but I don't see the point. I'm sure they know how to use their diagnostic tools, and I'm sure they're truthfully reporting what they found. It is less empirically documented, but I'm also sure that within the normal range of human behavior ("hey, maybe it's that trailer we welded to the back bumper!), we're driving the way we used to when our mileage was 25 percent better (give or take).

For now, I'm going to have to accept that there is no explanation. But if you've heard of any other instances of Prii losing their mileage magic as they age, please be in touch. (E-mail link at top of page.)

Author and wellness innovator Michael Prager helps smart companies
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