Lets be honest, just what does "thrashing" a rental car actually mean on the roads anyway?
Was kinda wondering this myself.
A lot on here seem to think that pushing the rev counter to its limits is thrashing the car and will cause it damage.
You're likely to cause more damage to the car through improper/no servicing than sticking to high revs.
The OP's looking at a fairly low mileage car, i would be looking at bodywork condition and the alloys, that's a better indication of how it's been driven. Any dings/scuffs/scrapes/scratches then i'd move on unless they were extremely minor, or the price discount made it worthwhile. Then as long as it's been fully serviced.