(Image source: Scoopertino )

BY CHRISTINA HARTMAN

Economic forecasts are a strange, strange thing. Case in point:

If the math is correct, say Apple’s upcoming iPhone 5 sells for $600, and $200 of it counts as imported components, that would leave $400 per phone to count in the U.S. government’s GDP measure.

And if Apple sells 8 million of the new iPhone 5s in the fourth quarter of this year, it could boost GDP by some $3 billion in the last three months of 2012.

That — get this — could mean a .33 percentage point boost in the Gross Domestic Product, which is the market value of produced goods and services.

It comes from a JPMorgan Chase economist’s report , which he titled “Can One Little Phone Impact GDP?”

His answer? Weeelll, yes. Think about it — what economist Michael Feroli is saying the newest iPhone could have a real impact on an entire country’s economic growth projection.

But even he recognizes the headiness of the projection, per The Wall Street Journal saying the estimate “seems fairly large, and for that reason should be treated skeptically” but adds: “We think the recent evidence is consistent with this projection.”

And it wouldn’t be the first time iPhone put the team on its back. Many credit the 4S with boosting U.S. retail sales in October .

Apple’s big media event is this Wednesday, where the company is expected to roll out the iPhone 5, with possibly a bigger screen, slimmer body new headphones and better camera. Those features are all just rumors for now, of course, but whatever it looks like — now there’s definitely more pressure on the little iDevice than better battery life.