Bike Boxes & Hire Cars

Mrs and I are off to Italy at May 1/2 term. Her for a relaxing 5 days, me to ride Monte Grappa & The Stelvio.

I’m renting a bike box and was wondering if anyone has any experience of getting one into a VW Polo sized car with the back seats down, or any car on that size, such as a Clio?

I’ll rent a bigger car if required but my wife would prefer to driver a Polo sized car.

Thanks in advance.