Jonathan Kletzel, head of the transportation practice at accounting and consulting firm PricewaterhouseCoopers LLP, said mergers don't necessarily lead to an increase in fares, and that from 2004 through 2011 a period that includes some of the biggest airline mergers domestic airfares actually decreased by nearly 1% a year when adjusted for inflation.

WSJ: American Air Stands to Gain Huge Route Network

Laviv, whose consulting firm focuses on securing mass transportation systems, is equally skeptical.

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Today GM still ranks as the top innovator among automotive and transportation companies, according to The Patent Board, a consulting firm which analyzes and values patents.

FORBES: How GM Lost -- And Found -- The Path To Innovation

After leaving office, in 2002, he started a consulting firm, Giuliani Partners, and embarked on a series of highly lucrative lecture tours, commanding the transportation (Gulfstream IV), the accommodation (a two-bedroom suite, plus four rooms for his entourage), and the remuneration (up to a hundred thousand dollars per appearance) accorded only to the highest tier.

NEWYORKER: Mayberry Man