The victim was a man aged 35 and was driving a Subaru Forester under the number plates KDC 010H.
A three-man gang that was riding on a motorcycle sprayed more than 10 bullets on the vehicle.
The motorist was rushed to the Thika Level 5 Hospital where he allegedly succumbed to his injuries.
A report filed by KTN News on Wednesday indicated that the motorist had two ongoing criminal cases, one in a Machakos court and the other in Nakuru.
The file in Machakos indicated that it was a robbery with violence case.
Experts suspect that the shooting was planned considering that it was done in broad daylight and nothing was stolen.
“It is not normal because criminals do not waste bullets in such incidences,” an expert stated.
Police officers are piecing together information to establish what could have led to the heinous act and who the perpetrators are.
The incident took place in the wake of rising insecurity cases along Kenyan Highways.
On Thursday, detectives from the Directorate of Criminal Investigations (DCI) arrested six more suspects linked to robberies of motorists and pedestrians along the Southern Bypass, Nairobi.
The Langata based detectives, in collaboration with sleuths attached to the Crime Research and Intelligence Bureau, used cyber and forensic analysis to track the suspects.