I was there last week and new multi story is very close, but across a windswept and wet open area, with no cover or direct walkway to south entrance.
The south entrance is relatively new, a single storey building with a very short gate line that doesn't really feel it was designed to handle busy periods.
Cardiff is an odd one operationally, nearly all the long distance services (from multiple destinations) terminate there, but none stop at a parkway, (or carry on to a parkway) as happens at Bristol, East Midlands etc.
A lot of the local stations (with a high frequency service to/from Cardiff Central) aren't great for parking, have you seen the size and condition of the car parks at stations like Cogan etc. Yes I know some car parks are free at suburban stations, but they are generally small, and further away, and if long distance train arrives late, and miss a half hourly service, can be over hour from long distance train to getting to your car. Not really an incentive to transfer at Cardiff Central.