With this really insanely vague description:
It would be an early to mid-90’s show, or possibly very late 80’s, and it would have been on broadcast TV, not just cable. The opening theme song was kind of jazzy. During the opening theme, there was a shot of a police car. There was also a shot of some sort of cartoon animal (a caterpillar or something?) with antennae being cheerfully washed down a bathtub drain. The bathtub may or may not be purple.
Googling ‘purple bathtub drain police cartoon’ and variants thereof is not as helpful as I’d hoped.
PS: It’s possible I just made this up, because I asked my sister, and she had no idea, but for all I know, she might have been growing out of cartoon-watching age by then.
Bonkers originally appeared as a slapstick character in a series of shorts on the anthology series Raw Toonage, then got his own show, where he was a cop hunting down toon criminals with human pals. The premise was similar to that of Who Framed Roger Rabbit- legend has it Disney planned a Roger series, but Steven Spielberg co-owned the character and was tough to work with.