Richard Boatwright felt "helpless" after the company refused to remove comments about his garage in Braintree, Essex.
He said: "We've provided them with firm information that shows these reviews are completely fabricated but they're not interested."
Google said the vast majority of user contributions were genuine and it constantly monitored content.
A number of one-star reviews about the garage appeared on Google's map service, such as: "Absolutely the poorest service I've ever been unfortunate enough to experience."
Mr Boatwright called it "an invisible aggressor".
"They're anonymous, behind fake names, so you don't really know what to do. You feel helpless," he said.
Google users post about 20 million business reviews each day.
The tech giant said: "The vast majority of reviews are helpful, relevant and authentic. We monitor closely for content that violates our policies 24/7."
Adam French from consumer rights organisation Which? said: "Our research has found fake reviews are prevalent across different platforms and the kind of influence they have on our shopping decisions is huge.
"I think there's more that companies like Google could do to shut down these fake reviews. They can be quite passive, relying on people to report them."
He advised customers to read full reviews rather than star ratings alone and to avoid relying on just one site.
"Look for things like repetition, odd turns of phrase, and check across different sites to see if reviews are saying similar things to get more of an idea if they're trustworthy."
Mr Boatwright said of his legal action: "We're not taking it lying down. We're trying to fight back but, for a small company to take on the mighty Google, it's not going to be easy".