Help me pick a new/used car

Ok, my 2006 Malibu needs at least $3000 worth of work and has 350,000km on the odometer. It hasn't been bad on gas - been getting 32mpg on my commute (I drive 75% highway, 25% city). Engine is fine.

I am trying to decide whether to fix the Malibu or get a decent used hybrid so the better mileage gas savings can go towards the monthly payments. Got it? Ok...

So far I have found:

a one-owner, no-accidents, nicely maintained 2009 Honda Civic Hybrid with 100,000 km on it and a brand new battery. (I am nervous about the recent battery lifespan claims since the battery is $2000+ and it had to be replaced after just 100,000 km)
OR
a one-owner, no-accidents, decent shape 2007 Prius with 90,000 km on it.

They are both $10,500 CDN.

Not sure what to do. They get about the same highway mileage (as posted by EPA and average user claims). Prius gets better in-town of course, but I don't do that much city driving.

What could I expect in ongoing maintenance for the 2007 Prius or the 2009 Civic Hybrid?
That will help me decide which will be the most economical including payments if I buy, plus gas and expected maintenance costs.

What kind of mileage would I realistically get with the Prius (including winter driving commuting across South Western Ontario with very little stop-and-go traffic? i.e. not Toronto)

p.s.
The Malibu is costing me an average of $1700 a year to maintain (primarily replacing brake pads, rotors, etc. due to the 40,000 km I drive each year).