A Con Ed middle manager used $4 million in illegal kickbacks from a contractor to buy two Mercedes Benzes and make big gifts to his wife and daughter, authorities said yesterday.

Sassine Razzouk, 53, earned about $150,000 yearly in his Con Ed job, which involved managing electrical and design projects, authorities said.

He faces a 10-year prison term on the charges, as well as a $250,000 fine.

Starting in 2008, Razzouk, a Staten Island resident, allegedly raked in millions more by demanding kickbacks from Rudell & Assoc., a Queens engineering firm.

The money Razzouk allegedly stole came from $18 million worth of contracts between Con Ed and Rudell & Assoc., say papers filed in Brooklyn federal court.

Rudell & Assoc. delivered the money by writing checks to shell companies that Razzouk controlled. Those companies did nothing but collect Rudell & Assoc. cash, the feds said.

After 11 other Con Ed employees were arrested in a smaller kickback scheme in 2009, Razzouk and Rudell & Assoc. tried to cover their tracks by adding a third shell company to the check-writing, say the feds.

Rudell & Associates’ president wrote the checks to a company he controlled that did no business with Con Ed. Then, checks were written from that company to the shell company Razzouk controlled.

Often, Rudell underbid the contracts in order to make sure it won the work, the feds said.

Once Rudell had the contracts, Razzouk approved additional payments, “often for work or materials that were requried as part of the original contract specifications,” authorities said.

Con Ed did not return a call for comment.