1-800-HowsMyDriving for nannies:

While nanny is minding the baby, passersby now can rat out a Mary Poppins who’s less than practically perfect in every way.

Under a plan pushed by a New York City prosecutor, all they’ll have to do is take down the “license plate” on the tot’s stroller and send an e-mail to the parents.

The plates are registered to www.howsmynanny.com, a site where informants can plug in the tag’s unique number to alert parents to a nanny’s indiscretions.

Unlike the vague, gossipy “bad nanny” sightings that proliferate on mommy blogs but don’t necessarily reach a tots’ parents, “There’s no guesswork. You don’t have to say, ‘Is this my nanny?’” said Jill Starishevsky, the assistant district attorney hawking the plates.

Buyers pay $50 for a 4-inch-by-7-inch plate and private access to notes from tipsters, who can remain anonymous.

Then there’s 1-800-HowsMyParenting:

Starishevsky admitted the system isn’t perfect: Parents could find themselves in the position of receiving reports about themselves.

“So when my husband is doing pop-o-wheelies with the stroller, someone can tell me he’s doing an illegal act?” joked Jo-el Shea, who was jogging with her 14-week-old son in Central Park this week.