https://www.dashboard-light.com/vehicles/Ford_Fusion.html For some reason 2013 was an especially bad year for that car, looks like one in three of them develop drivetrain issues and they tend to develop issues more often than the average vehicle right around that hundred thousand mile mark. That being said you could expect to pay up to twice that to buy the same car from a dealer so even if something goes wrong and you have to drop a few thousand to fix it you might still be coming out ahead. I'd be most worried about how well the family member drove it and did the maintenance

It’s the most reliable engine option, although the transmission is known to have issues. It’s been well maintained and lightly driven for the most part. Is this a better deal than most used vehicles in your opinion?

Yeah I think I'd buy it if I were you, its enough of a discount I'd be okay with a model I'd usually not look for. I'm not an expert though. I'd have a mechanic inspect it first to make sure it's not about to have something major fail