I didn't know that Volvo even made a hitch for a C70 as most people who install them put them on wagons. The reason why I've seen where people previously didn't like Volvo hitches was because they usually wanted to use a square type aftermarket hitch mount bike rack and those wouldn't work on OEM hitches from Volvo. This year, Volvo has finally changed that and is now offering a square hitch that (hopefully) is a universal size so that the aftermarket bike racks will work with them. Volvo also offers their own hitch mounted bike rack too.

As for wiring, although the Euro type plug might look good vs having a cord hanging out from the t-gate or truck in your case, we don't install them by choice because in the US, every trailer has a 4 pin flat plug and if the Volvo then has the Euro plug, an adpator cord must then be made (more work than necessary IMO). We typically install the 4 pin flat type convertors and have no problems with them. I'd also have to think that the Euro plugs exposed to the elements in areas with alot of moisture and salt will corrode within a short time whereas the 4 pin type's inside the car and kept dry.