NFL

Jets’ blemished coach has to shine up his game

A new coach is like a new car in a lot of ways. In the showroom — and the press conference — there is nothing to dislike. Everything is new. Everything is perfectly polished. Everything works. You want to show off your new car? A football team wants to show off its new coach.

Look at how fast she rides! (Look at how funny he is!)

See how sharp she looks! (See how smart he is!)

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At first, neither can do any wrong. And even when things do go wrong, there are excuses, and there are outs.

I’m not used to driving such a stylish machine! (Me and my players, we’re still getting to know each other!)

It never lasts forever, of course. Your ride gets a flat. The satellite radio doesn’t work. The brakes squeak. The seats don’t seem near as comfortable as they did on the test drive. And it gets dinged. And dented. And scratched up. Do you love your new car as much when she isn’t quite so perfect anymore?

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Coach Rex Ryan spent a lot of time as everyone’s favorite sports car. He was glib, which after Eric Mangini made it seem like the Jets had just hired a cross between Don Rickles and Jerry Seinfeld. He talked about playing some get-after-it defense, then when the Jets started the season by playing some serious get-after-it defense, he was revered as some kind of football Dalai Lama. Back in Week 2, when he implored Jets fans to scream at the Patriots, he was hailed as a shot-and-a-beer pope of the people.

It took a few weeks before the first scratches appeared. And then a few more. And a few more still. His rookie quarterback imploded a couple of times. His clock management skills seemed drawn straight from Herm Edwards’ guidebook. The defense — his defense — didn’t show up in Miami. He allowed his kicker to keep kicking to Ted Ginn Jr.

And when he tried to make a joke about Jets fans coming out to the Meadowlands tomorrow, imploring them to bring their “A” game for a change . . . well, the punch line fell flatter than the laugh track from “Accidentally on Purpose.”

So with the Jaguars visiting, this is the weekend Jets fans may make their own kind of determination, after filling the Meadowlands with the kind of fervor they always have been known for (as even Ryan himself gladly concedes). Win, and the honeymoon is extended at least another week, same as their playoff ambitions are extended another week.

Lose?

Well, it won’t just be the tires Jets fans will want to kick.

“You can’t have a good practice or a good game and then all of a sudden, one or two plays, [say] ‘But if this doesn’t happen or that [doesn’t] happen we’d be 7-1, or whatever,’ ” Ryan said yesterday. “The fact is, those things have happened. We’re tired of making excuses. We don’t need to make excuses. We just need to play better and find ways to win. I think that’s the message to our team.”

It needs to be the message for the coach, too. Ryan did everything in his power to try and alter the Jets’ thick culture of failure and excuse, and he had the team flying for three weeks. The hovering issue right now is convincing the Jets they really are 4-4, even if everything about their season insists they should be 6-2. They lost the Bills game. They lost to the Dolphins before the break. Those games aren’t coming back.

But there are eight games ahead. And those eight games won’t only define the 2009 Jets, they will go a long way toward establishing just how in love Jets fans are with their coach. He needs to hammer out the dents. He needs to do that quick.

“It is the stretch run,” Ryan said. “The beginning of the stretch run, but that’s what it is. There’s got to be that sense of urgency. Don’t wait for somebody else to make the breaks for you. We’ve got to do it ourselves. We understand that.”

They better. Far as we know, coaches don’t qualify in any cash-for-clunkers programs.

michael.vaccaro@nypost.com