The lead sponsor of the Grand Prix of Boston is revoking its name and funding from the canceled IndyCar race, as new questions emerged about whether the local promoter exaggerated financial support for the event.

LogMeIn, the Boston-based Internet company that bought naming rights for the race, sent notice it was canceling its contract with the Grand Prix of Boston and would be asking for refunds, company officials confirmed.

The firm had already provided $375,000 for its sponsorship and was expected to deliver another $375,000 by June 30, according to a sponsor list Grand Prix was circulating. LogMeIn also was developing a special app and software to showcase at the Grand Prix.

Sources told the Herald other Boston businesses have moved to distance themselves from the race and cancel their sponsorships in the wake of the promoter’s abrupt decision to scrap the race.

The Grand Prix sponsor sheet, obtained by the Herald, shows CEO John Casey claimed to have secured more than $16 million in cash and in-kind services and trade from its business sponsors.

Casey had been distributing the spreadsheet recently to show the race was in good financial shape, but several businesses that were listed as sponsors told the Herald they never signed on with the race.

John Hancock, the Boston financial services giant, was listed as pledging $200,000 for a race sponsorship, but a spokeswoman refuted that claim.

“We are not a sponsor and have not been,” Hancock spokeswoman Melissa Berczuk said.

Harpoon Brewery was listed on the Grand Prix’s sponsor sheet as pledging $40,000 in cash.

“That is not accurate,” Harpoon communications director Liz Melby said. “They did reach out to us with sponsorship opportunities but we did not accept or commit to a sponsorship at any level.”

A spokeswoman for Legal Sea Foods, which the Grand Prix said had contributed $5,000 and would be making another $45,000 donation in services, said the restaurant group did give $5,000 but only estimated its in-kind donation at $21,000.

Other sponsors on the Grand Prix’s internal list included Lamborghini at the $80,000 level, Martignetti Liquors at $200,000, Leader Bank at $150,000 and The Boston Globe at $40,000 in “products/services.”

But according to the document, Casey was not expecting to collect the vast bulk of that $16 million in sponsor commitments until after June 30, raising questions about the promoter’s financial abilities.

Casey had been trying to revive the race this week, and was looking at Suffolk Downs as a new IndyCar venue, sources have told the Herald.

But on Thursday, Mayor Martin J. Walsh and the head of the national IndyCar circuit ruled out holding a race this fall, effectively killing any hopes of holding it with the Grand Prix of Boston and Casey at the helm.

Casey could not be reached for comment and his public relations firms say they are no longer working for him.