The hidden cost of hybrids

Owners of 'environmentally friendly' hybrid cars like the Toyota Prius and Honda Insight may be hit with a bill for up to $7000 when their car's battery dies less than eight years after purchase. The battery unit, which has a lifespan of 8-10 years -- shorter in hotter climates like Australia -- cannot be reconditioned. It must be thrown out and replaced with a new one, at considerable cost to the owner.

"A replacement battery on the Insight retails for $6840," said Honda spokesman Mark Higgins. Honda began selling the Insight hybrid in Japan car in 1997 and in Australia in 2000. It sold 44 Insights before withdrawing the futuristic-looking two-door coupe from the market earlier this year. Honda will re-enter the hybrid market with the Civic sedan in March, and aims to sell around 20 per month.

My last car was ten years old, with 170,000+ miles on it, when I finally replaced it. I want to keep my current car for ten years or thereabouts. And the total maintenance expense over the last five years of my car's life was certainly less than the cost of one Insight battery.

I didn't buy a hybrid car for two main reasons: most of these miles come from highway driving (where the hybrid's mileage advantage isn't as good), and I wanted to see how maintenance costs for these cars develop. In five years, it should be clear whether or not these cars are a good investment.