The attackers pumped at least 40 bullets into the vehicle killing the driver and his passenger instantly. The victims aged 42 and 37, were from Vladikavkaz in Russia's North Caucasus Republic of North Ossetia and were involved in the wholesale alcohol trade.
"The criminals virtually riddled the car with bullets," the source said.
According to preliminary reports, the murders are thought to be linked with their business activities.
This murders smack of the 1990s, a period characterized by lawlessness and mafia rule, which left thousands dead in organized crime killings. The number of contracted murders is currently on the rise in the Moscow capital.
Police cite at least two possible contract murders in November. On November 7 unknown assailant shot dead a Croatian man, a co-owner of a construction company, near his apartment in southeastern Moscow.
On November 29, unknown attackers shot a Russian businessman at point-blank range, while he was getting out of his car.
Early on Monday, an explosive device, planted under a Volvo car, went off in eastern Moscow, injuring the driver. According to preliminary reports by Russian media, the car owner was an official from the Russian agriculture ministry. No links to an attempted contract murder have been confirmed so far.