As an 11 or 12-year-old, his mother taught him to drive by letting him behind the wheel of their US-made Essex for the 50km gravel-road drive from their Waimate home to Timaru.
"All I knew was to give way to the right, and if in doubt, jump on the brakes," he recalls.
Mr Mitchell started a sheet metal apprenticeship in Christchurch in 1928 - the year Alexander Fleming discovered penicillin.
The 15-year-old got his driver's licence and immediately began saving his half-crown weekly wages.
His first motorised mode of transport was a BSA motorcycle, which he explored the South Island on.
Shortly after the outbreak of World War Two, he bought a stylish 1936 Chevrolet coupe, which he again travelled across New Zealand during breaks in his training as a Royal New Zealand Air Force engineer.
Going off to war, brother Harry was tasked to sell the beloved car.
But on Mr Mitchell's return from serving in the South Pacific, his car was still there.
"Harry ran it every day. It was great to come back to."
In 1947, he hit the road again, this time for his honeymoon with new bride Kathleen.
They spent 62 years together, and had three children, before she died "in my arms" in 2009.
The Mitchells enjoyed a shared love of cars, and owned many throughout their life together: a Vanguard, Morris Eight (Series E), Hillman station wagon, Chevrolet Chevette, Ford Capri, Rover TC 2000, Austin Allegro, Austin Mini 850.
After the war, Mr Mitchell owned several Christchurch grocery shops before driving taxis.
He first drove an ageing Holden before buying a Wolseley 16/60.
Once he picked up a fare who turned out to be an old war-time mate.
During the journey, his friend revealed that his wife had just died after her car's brakes had failed and she went over a cliff.
"I got such a shock I jammed the brakes on and got rear-ended," Mr Mitchell said.
Remarkably, that's the only road traffic accident he's ever been involved in.
Mr Mitchell is one of just four current driver licence holders in New Zealand aged 103, according to NZTA figures. None are older than 103. There are 24 drivers aged 100-plus, and 361 aged 95 and over.