Each CW-80 is rated at 5 amps and should be able to adequately handle the loops you mention, although the 2.5 amp draw for one loco and passenger car seems on the high side depending on the loco and if that's continuous draw. You might want to check the loco and car to make sure everything is moving freely and clean the track.
Personally, I wouldn't recommend anything until and unless you start experiencing a problem. I've had 2or 3 engines running at one time off a CW-80 and not experience any issues. If you have issues or want to step up, I would recommend the MTH Z-4000 transformer as an upgrade. It's fairy reasonably priced for a top transformer and has two separate throttles, each of which you can wire independently to your separate loops and it provides 10 amps per throttle.
