Chevrolet and Man Utd: $600 million deal a 'no-brainer' says fired GM boss

Ewanick said it was clear that the deal would bring Chevrolet increased brand exposure, purchase consideration and awareness around the world worth "over four times" the sponsorship's cost.

According to AdAge the cost of the deal was around $600m over seven years.

Ewanick was dismissed within weeks of the announcement of the Manchester United deal. A spokesman at the time said that he "failed to meet the expectations the company has of an employee."

Ewanick is sticking to his guns. At the J.D. Power Automotive Marketing Roundtable in Las Vegas, he said: "We crunched more data than I've ever seen. We had three separate media and consulting firms take a look at it and tell us what they thought it was worth. We had the internal GM team do it.

"The way this was going to work over time, I would say that for the amount of money we were talking about, it was the biggest no-brainer I've seen."

The Manchester United sponsorship is one of the few major Ewanick initiatives that has stuck at GM.

Ewanick joined GM in May 2010 to oversee the company's U.S. marketing operations and was named global chief marketing officer by the end of the year.

His tenure as GM's global marketing boss was "tumultuous. His outspoken, hard-charging style sometimes ruffled the feathers of superiors and co-workers," said AdAge.

Previously, about 125 markets around the world each had its own sales and marketing budgets, he said. Ewanick described the process of consolidating and reallocating those budgets as "going around the world saying 'I'm going to take your budget away.' They weren't very happy about that."

Since leaving GM, he has worked with a number of car companies behind the scenes while living in Newport Beach, California.