The RPG myth didn't bring much to the table. I think most of us have watched this show enough/long enough to know how explosions work especially when versing movie scenes with reality. Which probably is why they didn't "duplicate the result" but just "made it look good." There's been one or two other instances over the years where a "Hollywood Myth" result test was done by simply showing the special effects behind it.
But in those cases, that was just the final bit after they'd tried to replicate the result for real and proven it simply couldn't be done. Here, they just skipped that step. They should've demonstrated that an explosion powerful enough to flip a car would more likely tear it apart instead. That would've been the most conclusive way of busting the myth. And it would've let them do more and bigger explosions, so it serves both the science and the spectacle. They just got lazy here.