Gran Turismo 5 was his game of choice and he admits he was pretty good at it. One day, as he loaded the game and sat down to play, a message popped up inviting him to take part in a time trial.
''And the rest is history really,'' the 22-year old Welshman said, after racing in the first of three Toyota Racing Series (TRS) races at Highlands Motorsport Park on the weekend.
• Slideshow: Toyota Racing Series at Highlands Motorsport Park
The time trial was run by the Nissan GT Academy, an international virtual-to-reality contest that offers the best Gran Turismo players the opportunity to become professional racing drivers.
''When I entered [in 2011] there were 90,000 people in Europe [competing] but last year there were over a million people in Europe, plus 900,000 in America.''
The competition was run in three stages, he said.
''The first, anyone with a PlayStation, Gran Turismo and the internet can enter. Then there are national finals, where the top 20 qualifiers are whittled down to two.''
Those two joined 10 other European national finalists at Silverstone, one of the top motor racing facilities in England.
''It was my first time in a sports car, my first time in a race car and my first time at a race track,'' Mardenborough said.
''I was on the complete bottom step in terms of experience.''
After a bit of training, he secured himself a spot in the training academy, ''and now I'm living the dream''.
''This is my passion. There's nothing I would rather be doing.''
This is his second time racing in New Zealand. He competed in the TRS last year. It was his first time at Highlands and he labelled it an impressive facility.
''Usually, in Europe, you would get a lot of run off but here there's a bit of grass or gravel, then walls, which is nice, because it's a challenge to drive. If you make mistakes, it punishes you and that's how it should be.
''The bridge makes it pretty unique, too.''
Speaking to the Otago Daily Times after the first TRS race on Saturday, he was ''a bit naffed off''. He had started the race in third place but dropped back to fifth.
An engine issue dropped him to 11th, but he managed to fix it in-race and clawed back a few places, until he went to overtake another car on a turn.
''He decided to keep turning and eventually we clipped. It ruined my race, so I'm a bit naffed off, really. It's kind of ruined my weekend.''
He started 18th out of 22 for the second race but a good qualifying time saw him take de facto pole position in the third and final race after Estonian Martin Rump was unable to start.
After winning the third race, he finished the weekend second in the TRS, two points behind Rump. TRS was his ''winter training'', but for what he could not yet say.
