I've got a 2015 Chevy Impala...the newer style. It's on an extended wheelbase large car, GM Epsilon II platform, which was mostly designed by Opel in Germany. The Cadillac, big Buick (LaCrosse) and Impala use this extended chassis. The Epsilon platform is in various sizes both for GM Euro and North American cars.
We've had ours since 2015 and in 42,000 kms have not had it in for more than oil , filter changes and tire rotations. Not one issue. The transmission is a regular (non CVT) style front wheel drive, 6 speed automatic. Believe both GM and Ford co designed this transmission and also the 10 speed rear wheel drive (non CVT) auto transmission that is used in both GM/Ford rear wheel drive platforms.
We have the 3.6 liter DOHC, 4 valve per cylinder V6 (305 hp) naturally aspirated fuel injection engine. Sort of a detuned base Camaro engine. Acceleration, high speed cruising, braking and handling are great. BTW, you can also get the 2.5 liter dohc 4 cylinder. The Epsilon ll platform has won a number of awards.
Gas mileage is quite good for a car this size and an engine displacement. It moves out well. I need a large car as at just under 6' 4" and 240 lbs...I just don't fit well in most cars. Shoulders hit the inside pillars of vehicles, head hits head liner...can't get seat back far enough for leg comfort. I have a bit of a wonky knee from a decade of ice hockey, playing defense when I was a kid. Canadian eh.
I fit with room to spare in our Impala.
Trunk room is enormous and we can add by putting the rear seat down.
If you're looking for a large car (probably not, I know) I would recommend you take a new Impala out for a test run.