The deal allows VW chairman Ferdinand Piech, who has long coveted Ducati and himself owns one of their superbikes, to make up for a missed opportunity nearly 30 years ago to buy the maker of the fire-engine red 1199 Panigale, which boasts the most powerful twin-cylinder production engine on the planet.
One source said Ducati's debt was well below 200 million euros in an acquisition analysts said lacked obvious benefits for premium carmaker Audi and did little but polish Piech's reputation as a collector of rare and exotic brands.
The Ducati purchase is driven by VW's passion for nameplates rather than industrial or financial logic, said Arndt Ellinghorst, analyst at London-based Credit Suisse.
It's an unnecessary sideshow to VW's main challenges of integrating sports-car maker Porsche
Ducati, which has won 13 rider's Superbike World Championships since 1988, will increase the VW group's brand portfolio to 12 and extend Audi's long-standing rivalry with Bayerische Motoren Werke
The purchase does have a trophy feel to it, in the sense of something you might mount up on the wall next to the stag you shot last year, said an auto industry analyst, who himself drives a Yamaha R1 superbike.
When exclusive Italian superbike rival MV Agusta was put on the block late in 2009 by a Harley Davidson
I would still like a small, valuable motorcycle manufacturer, Piech revealed in an interview with a German magazine from April 2008, complaining that he should have jumped at the chance to buy Ducati in 1985 when it cost peanuts.
Audi and Investindustrial may agree to withhold the exact purchasing price in the statement, which they plan to publish on the eve of VW's annual shareholders' meeting in Hamburg, one of the sources said.
DROP IN THE BUCKET
Outgoing owner Investindustrial last listed Ducati's earnings before interest, tax, depreciation and amortisation (EBITDA) at 71 million euros for 2010, on revenue just above 390 million - a drop in the bucket for Germany's most profitable manufacturer.
Ducati makes about 40,000 two-wheelers a year across its range of cruiser, supermoto, adventure, naked and superbikes that include the muscular Diavel and dual sport Hypermotard. By comparison, industry leader Honda <7267.T> sold over 16 million motorcycles last year.
Demand for large sportbikes has contracted sharply following the financial crisis, with hobby riders less willing to shell out perhaps 10,000 euros or more for an expensive toy.
The market halved since 2008 and still shows no real sign of recovering, said Rudy Probst, a spokesman for BMW's own motorcycle division.
Motorbike technology has only a very limited crossover to car manufacture, so Audi is unlikely to see any direct benefit, and though technology transfers flow more often in the opposite direction, there are cultural limitations.
Bike makers place much less emphasis on fuel efficiency and lower emissions, the major trends in the car industry. Instead sporty motorcycles are designed for extreme acceleration, breakneck speed and tight cornering.
Filling my bike used to cost 18 euros. Now it's 25, and if it goes up to 35 euros, I'm still not going to care. My R1 takes about three seconds to go from 0-100 kilometers an hour, all in first gear. That's why I bought it, said the industry analyst.
Antilock brakes (ABS), which have been standard in all new cars for years, are a prime example. Only in the last 18 months Bosch
Integrating new technology into the engine of a motorcycle is often a question of weight; it's easier for cars to add on a few extra kilos than a motorbike, where handling would suffer, Probst said, adding variable valve timing was another fuel-saving feature yet to be really embraced by motorbike owners.
Other aspects like traction control cannot simply be adopted directly from their application for cars. Extra expenditure must be spent to adapt it to the different physics of having two wheels on the road as opposed to four, he said.
David Arnold in specialist sales at Credit Suisse doesn't see the logic, either, but can't begrudge Volkswagen the luxury of splashing out for Ducati, since it has such a strong track record of reviving tarnished brands such as Lamborghini.
VW would likely say that cylinder head design in the motorcycle industry is much more advanced than in passenger cars, a common argument, but that sounds a little bit farfetched to me, he said.
Analysts say VW chose its luxury brand to buy the brand since Audi can claim rival BMW also has a motorcycle business to enhance its sporty image, thus lending the deal a figleaf of justification.
Barclays Capital analyst Michael Tyndall, himself a self-styled Ducatista, said the deal showed just how much VW's 17 billion euro pile of cash was burning a hole in its pocket.
It shelled out 6.63 billion for equity in dealership group Porsche Holding Salzburg, truck maker MAN and still had 1.1 billion left over after its normal year-to-year investment needs.
Consider for a moment that Volkswagen's business generates something close to 8 billion euros in free cash every year. The company either has to find investments to enhance its return on capital or it needs to return the extra cash to shareholders, Tyndall said.
($1 = 0.7656 euros)
(Editing by Helen Massy-Beresford and Will Waterman)