USING THE CPK BROWSER, NAVIGATE TO C:Program Files (x86)/Dragon Ball Xenoverse 2/cpk, OR WHEREVER YOU HAVE THE GAME INSTALLED, AND CHOOSE DATA.CPK.
IF YOU'RE UNABLE TO FIND CAR_BGM, I SUGGEST YOU USE A CPK BROWSER TO EXTRACT IT ( Link to CPK Browser ). MAKE A BACKUP OF CAR_BGM FIRST, BEFORE DOING ANYTHING ELSE