You know you’ve launched a winning product when it’s selling like hotcakes all across the world. You can be even more confident when it’s a luxury product like the latest 2011 BMW 5-Series Sedan, which is currently sold out worldwide.

In fact, customers looking to hop into the new 5-Series are being forced to wait between three and four months for delivery of their vehicle.

“The 5-Series is at the core of the BMW brand and we knew it was going to be a very strong vehicle for us,” BMW sales chief Ian Robertson said in an interview with Bloomberg. “In the U.S., where it’s doing very well, it could come to between 15 percent and 17 percent of our business as we ramp up.”

That’s pretty impressive for a vehicle that starts at $50,475 (including delivery) and has only been on sale for less than a week.

Many of the sales are being stolen from Audi’s A6, which is really starting to show its age against this new 5-Series and the Mercedes-Benz E-Class, which was updated just last year. Demand for luxury vehicles has also rebounded from last year’s lows following the global financial crisis. BMW’s sales in May, for example, are up 11 percent for the same period one year ago.

You can check out our first drive report of the new 2011 BMW 5-Series by clicking here.

[Bloomberg]