How are the tires on your current vehicle?
Driving long highway trips is... well, not 'good' for a vehicle (unless it's a diesel that needs 'cleaning out'), but certainly less stress than 1000 miles of puttering around town. It'll get everything up to a really good temperature, get moisture out, etc.
I'd certainly take my own vehicle. If you're in QC it'll likely rust out before it 'dies' anyway... well, that's an assumption as I don't know how you look after it (rustproofing), store it (garage), maintain it, etc. But... for the hassle of getting, faffing with rental company, etc, I'd just get in my own car and drive.