Paul Kariuki Ngugi was shot at more than 10 times as he drove on Forest Road in the company of a woman.
The woman suffered a gunshot wound to the head and was still unable to speak to the police on Thursday as investigations continued.
When police arrived at the scene, they said they found the woman lying helpless next to the man’s blood-soaked body in the car, long after the gunmen had fled.
Commenting on the murder, Gigiri CID boss Daniel Kandie said, “We do not know the motive of the shooting because the attackers escaped soon after their mission. Investigations are ongoing.”
The business man’s bullet-riddled car was towed to the Parklands Police Station.
In a separate incident on Thursday, a man was shot dead during a robbery in Nairobi’s Lang’ata estate.
According to police, the man was gunned down as he raised alarm as the thugs escaped after committing the robbery.
The gunmen were escaping after a 6am robbery at an apartment within Ng’eno estate when they met the man outside.
With cases of executions becoming rampant, detectives are keen to arrest the criminal gangs said to be skilled hit men operating within Nairobi.
Police are still investigating last month’s killing of George Muchai who was the Kabete MP and his three aides along Kenyatta Avenue.
The four were sprayed with bullets at close range at about 4.30 am when their vehicle slowed down at the Nyayo House round about.
Six suspects have since been arrested though police are yet to file charges against them.