Police said they spotted two drivers racing each other, reaching speeds of up to 120km/h in a 80km/h zone, along the Great Western Highway at Kingswood just before 11pm on Saturday.

When officers stopped the drivers, they discovered two children, aged three and 18 months, unrestrained in the back seat and the wife of the driver in the front seat of a Toyota Kluger.

The 33-year-old driver was charged with street racing, exceeding speed by limit by more than 30km/h, not carrying a licence, not displaying P-plates and two counts of driving with a passenger aged six months to four years not restrained as prescribed.

His licence was suspended on the spot.

The driver of the other vehicle, a Jeep Grand Cherokee, was the only person inside the car.

The 27-year-old was was given a future court attendance notice for street racing and exceeding the speed limit the more than 30km/h. Police seized and suspended his license.

The arrests follow a horror few days on the state's road, with multiple fatal crashes since Friday.

Dr Vincent Wong, 76, and a 26-year-old man died after a crash between a motorbike in Lane Cove in the early hours of Saturday morning.

Superintendent David Driver said it appeared the 26-year-old motorbike rider had gone through a red light at high speed and collided with Mr Wong's car.

In Sydney's south west on Sunday morning, a driver died after their car crashed into a tree and caught alight at Badgerys Creek Road at Bringelly.

Also on Sunday morning an 18-year-old man who was hit by a B-double truck in Seven Hills overnight died in hospital.

A 17-year-old man died in hospital after a two-car crash on the Princes Highway at Wandandian south of Nowra on Saturday afternoon, and a 75-year-old man was killed after a collision on the Motorway Link Road on the Central Coast about 1pm Friday.

A passenger also died at Dapto, in the Illawarra region, on Friday after a car crashed into a tree. The vehicle caught fire and residents managed to free the driver, but the passenger was trapped and died.