Little Daewood Hewitt was in the passenger seat of the Seat Leon which had suffered from gear problems and ground to a halt near Hilton Park Service Station.
The accident happened between junctions 11 at Cannock and 10a at Essington on the afternoon of Bank Holiday Sunday, May 26, last year. Daewood was airlifted to Birmingham's Children Hospital where he died the following day.
Thomas Fryer has been charged with causing death by dangerous driving and has gone on trial at Stafford Crown Court.
At the opening of the case yesterday it was said Fryer had been clocked doing speeds of up to 90mph in the Mercedes he was in further along the southbound carriageway.
Mark Heywood QC, prosecuting, said mother Alicia Shaw had struggled to get the car into fifth gear after getting into the third lane.
She tried to change into other gears and the car came to a halt on the motorway. Other cars on the motorway became aware and were able to go into the inner lanes avoiding the obstruction.
However, Fryer, aged 31, of Duncroft Road, Garretts Green, Birmingham, didn't and crashed into the Seat Leon which was also carrying two other children. Daewood, of Milton Road, Cannock, was the only one who was seriously injured.
Mr Heywood said: "When the vehicle immediately in front of him moved into the inner lanes he didn't manage to do so in the same way.
"The prosecution say his failure to avoid that vehicle arose from a series of failings on his part. For some miles behind he had been travelling at speed, some what in excess of the speed limit."
He added it is not uncommon for hazards on the M6 and it is something motorists should guard against, with Fryer's driving fell below the standards expected.
A statement from Alicia was read out at court and she said the hazard lights were put on when the car suffered problems.
She said: "I was in the fast lane and I started to look in my rear view mirror. At least 15 cars appeared to have seen me at the last minute and went around me.
"The car ploughed into the back of my car. The car from behind approached at speed and took me out. There was an almighty bang and my car was spun around."
She said she was unable to get her baby from the vehicle and then other motorists who were on the M6 came to their aid.
The trial, which is expected to last until the middle of next week, continues.