We had both a Prius and a Matrix at the same time. The Prius will fit two big dogs in back (ours are each 70+ lbs) with the seats down, but it's all carpeted, so clean up is a pain. Plus, put two dogs in the car and a bike rack with two bikes on a trailer hitch (what we did) and you can watch your gas mileage drop down to regular car levels (mid 30's) on the highway. Those bikes act like sails and when you lose the aerodynamics of the car, you lose a lot.

That said, there are lots of owners out where with batteries that have lasted well beyond 100K miles. They are only warranted to that age - but that doesn't mean they immediately quit working then. This is a Toyota, you know. And, when gas gets back up to $4+ a gallon, the cost comparisons shift pretty drastically.

That said, we did sell the Prius last fall and kept the Matrix. Ours were both the same year (2005), but the Matrix is bigger on the inside (two dogs in back with the seats still up) and it does MUCH better with the bikes on the back because of the profile of the car. Where the Prius dropped from 46 mpg to 34 mpg (highway), the Matrix only dropped from 33 mpg to 31 mpg. The cargo space of the Matrix is also plastic - so easy to clean up muddy footprints. We also like that our Matrix (don't know if they kept this with new models) has a hatch glass that will open independently of the hatch opening. This makes the cargo space accessible even with bikes on the hitch.

We have 75K on our Matrix and it's still riding like new. Outside of a slightly odd clutch that takes some getting used to, we have not a single complaint about the car. We consistantly get about 31 mpg and we drive mostly back roads. We will average about 33 mph on the highway.