The Honda Fit engine probably will last way over 250,000 miles
(or 20 years) if you take care of it. If you garage the car and
don't get into any accidents the body will probably last just
as long (but the cloth seats will be unraveling by then). The
Fits nicest ergonomic feature is the "magic" seats. Sometime
in the next three years Honda plans to introduce a mild hybrid
version of the Fit.
I still have a 1990 Honda Accord LX albet its body is a bit rusty.
It been hit multiple time and now has a salvage title but it
still get 22 mpg (down from 25 mpg when I got it new).
Honda's weakest components are the alternator, electric
motors (e.g. power windows, power antenna). While the
stero cassette tape player gave out on the 10th year but
the FM radio still works after 20 years. Due to road salt
during the winter - the lower suspension and exhaust
system are prone to rusting away. To keep the front
seats in good condition I have seat covers over them.
It's not how may miles but how old the batteries
are that seems to matter. In Prius forums, I've
read a few account of 1998-2003 Prius High
Voltage(HV) traction battery are dying after about
8 to 11 years of service. Of the sporadic accounts
I've read the mileage when the battery fails
varies greatly. FWIW - extreme temperatures
and draining the batteries to a very low tends to
accelerate the aging process for a battery.
I've also read that the regenerative braking
system tends to extend the life of the braking