NEW YORK —  If sex sells, then same-sex sex appears to sell super well.

A much-promoted lesbian kiss on the stylish, LA cop drama Fast Lane between hottie Tiffani Thiessen and guest star Jaime Pressly gave the struggling series a huge, much-needed ratings boost last Friday night.

Ads promoting the episode — including a quick glimpse of the steamy girl-girl lip lock — had been running all last week in Fox, the network that airs Fast Lane.

Basically, the show's ratings jumped by a third among adults 18-49, the viewers advertsiers want most.

More significantly, in its target audience — viewers 18-34 — ratings were up more than 60 percent, officials said.

"It was pretty significant," Fox TV chairman Sandy Grushow said of the ratings hike.

The network reently moved the rookie series from Wednesday to Friday nights in search of a more steady audience..

Thiessen said the kiss wasn't a big deal to her — even if it generated so much public heat.

"I didn't mind it," she told The Post. But the strong reaction "does surprise me to a certain degree. It's been done so many times before," she said.

She said she couldn't avoid noticing the network's heavy promotion of the lesbian kiss. '

'It's Fox and they love to make a big deal about something like that," she says.

In last Friday's episode, the undercover cop played by Thiessen has to infiltrate an all-woman's valet car parking service led by Pressley's character.