Unfortunately, all 4 doors don't open on the UT Impala SS models. Yours might be the Impala SS 510 Concept from AUTOart where all 4 doors open. That's a much rarer and pricier model these days.Yup, still a great diecast from back in the day. And one of a few from the time where all 4 doors open. If I recall correctly, as mine is stored away now, it's the '96 version which used analog gauges and the floor shifter. Much nicer than the digital gauges and column shifter.
Oddly enough, the rear doors on the UT models were a separate piece glued on, making me wonder if modding it to open might be a possibility.