Bernie Ecclestone's bruising approach to business has always belied his inches, and his willingness to take on any adversary, whatever their size, has made him enemies over the years. But few could have predicted it would be a consensual deal in which he cashed in his remaining stake in Formula One that would ultimately land him in hot water.

Yet, after being named in German court papers as the alleged payer of a $44m (£27m) bribe to Gerhard Gribkowsky, a former senior executive of the German bank BayernLB, Ecclestone is in the tightest spot of his long and lucrative career. The allegations, which further claim that in return Ecclestone received $41.4m in commissions along with his family trust taking $25m, relate to the 2005 deal under which CVC Capital Partners, a private-equity firm, took control of Formula One.

BayernLB was a reluctant investor in the sport, having acquired the 48% stake as the chief creditor to Kirch following the collapse of the German media giant in 2002. When CVC offered to buy the stake in a $1.7bn deal three years later it seemed to suit all parties: CVC was taking over a business that generated enormous amounts of cash, BayernLB could return to being a lender, not an investor, and Ecclestone could dispose of the remaining 25% of Formula One that he still owned.

In the eyes of many the deal changed little since Ecclestone remained the chief executive of Formula One Management, the sport's operating company, which effectively runs Formula One, and CVC's principal negotiator with the teams.

Spool forward six years and Gribkowsky has spent the past seven months under detention in Germany. He stands accused of receiving the $44m bribe from Ecclestone, who remains chief executive of Formula One Management, to sweeten the deal. "According to the result of this investigation, this is bribery money," said Barbara Stockinger, the spokeswoman for the Munich prosecutors who have brought the case, in a statement as charges were pressed against Gribkowsky on Tuesday. "These payments would not have been asked for were it not for the bribes to be paid to the accused. The Bayerische Landesbank [BayernLB] incurred damages of almost $66.4m through the conduct of the accused."

Ecclestone, Stockinger told the Guardian on Wednesday, "is still under investigation". Even so, few in the sport expect the 80-year-old, whom the Guardian could not contact on Wednesday but who denies wrongdoing, to be arrested in connection with the case.

As a measure of Ecclestone's concern, he is indeed expected to attend the German Grand Prix at the Nürburgring this weekend. "Of course, why should I not go? Why would you arrest me? There's no reason," he said on Tuesday.

But the developments surely make even the indomitable former second-hand-car dealer uncomfortable. If Ecclestone is, at a reasonable minimum, called as a witness in the case against Gribkowsky there will be difficult questions to answer. Neither of CVC's Nick Clarry and Tim Gallico, who are both directors of the group companies that administrate Formula One, returned the Guardian's calls on Wednesday.

Meanwhile, there are numerous unknowns, among them whether CVC believes its investment to have been worth all the hassle of the past six years. For this is not the first controversy it has faced. In 2008, amid concerns about the level of debt that had been loaded on to the sport during CVC's highly leveraged buyout, the teams warned they would set up their own breakaway series.

It was an existential threat to the business of Formula One, which led to the birth of the Formula One Teams Association, giving the constructors for the first time a credibly united front against Ecclestone and the sport's operators. Ultimately the hatchet was buried in the shape of the 2009 Concord Agreement.

It is believed this deal, which runs until the end of the 2012 Formula One season, stipulates that the teams may not take steps to or even discuss setting up a rival championship during the term of the Agreement. But the added security came at a heavy cost to CVC. Where previously the teams had been forced to make do with sharing only 47% of the sport's television income, now they could feast on 50% of all the sport's cash profits from every area of its operations – advertising revenues, merchandising and licensing, as well as broadcasting. The added benefit of being able to place nonexecutive directors on the CVC board and of receiving full disclosure over the sport's finances appeased the teams.

"All the major challenges the teams faced have been met," a leading analyst in Formula One said. "To improve their position today would be quite difficult. The teams have got what they wanted."

The result of the hard bargaining by the teams made CVC's investment far less lucrative than at the time of the 2005 purchase. Although by raising revenues from races and cutting costs CVC has made Formula One more efficient, the amount of cash they could have potentially taken out has fallen sharply.

In 2007 payments to teams amounted to $342m but rose under the 2008 Concord Agreement to $521m. In 2009 these had risen again to $544m – in 2010 CVC chose not to disclose the amount.

In the meantime, the net debt of CVC's Formula One investment vehicle has risen far in excess of $5bn, although that does not represent financial distress since most of it is parent-company loans, and CVC can afford that. But as the teams head back to the negotiating table over the 2012 Concord Agreement many are sensing a potential weakness in CVC, whose fortunes have been so tied to those of Ecclestone. Seldom has the octogenarian corporate warrior been so on the back foot.