After success in karting he won the British and European Formula 3 championships in 1991, before racing in Formula 3 and Formula Renault. In 1996 he entered the Renault Spider championship, and a dominant title win saw him earn the second drive in the Williams-Renault BTCC team.
He made a sensational start in the Laguna, taking pole for his first 3 races, and ultimately winning 2 races as a rookie, taking 3rd in the championship won by team-mate Alain Menu. He was 5th in the series in each of the next 3 years, having joined Vauxhall in 2000. For 2001 the series had a new set of reduced-cost rules, less big-name drivers as a result, and Vauxhall had by far the best car. In a contentious and hard-fought season, Plato won the championship after team-mate Yvan Muller's car set alight at the last round.
With an ambition to get into NASCAR racing, Plato moved to the British ASCAR stock car scene in 2002, finishing 3rd in the championship.
He was employed by SEAT to help with their driver development in 2003, and when they entered a BTCC team in 2004, he was the natural choice to lead the team. He was third in the championship that year, winning more races than anyone else, although the team used the reverse-grid regulations to their advantage. The driver finishing 10th in the first of the meeting's 3 races had pole (and a light car) for race 2, and the winner of race 2 had pole for race 3 (although with a now-heavier car), so Plato frequently dropped back to 10th in race one, often going on to win races 2 and 3. As a result of this, the championship rules were changed to reversing the top 10 of the race 3 grid, somewhat scuppering this tactic, and the pace of Matt Neal's Team Dynamics Honda and Yvan Muller's Vauxhall left him unable to challenge for a second title. In 2005 he finished 4th in the Championship with three wins to his credit.
For 2006, Plato continues in the British Touring Car Championship as lead driver for SEAT and their new León touring car. He will be the only driver in the three-driver team to compete in all 30 rounds - his team-mates, two times BTCC champion James Thompson and ex-DTM driver Darren Turner, will share the team's second Leon. After the first 3 meetins he was a point behind Thompson in 3rd in the championship, and two retirements in the races at Thruxton did not help his cause. After winning race 1 at Croft, race 2 was his 200th start, and it was nearly a glorious one, before Matt Neal passed him with 2 laps to go. He won 2 out of the 3 races at Brands Hatch to keep his faint hopes of winning the BTCC in 2006 alive.
Plato can also be seen presenting the Channel 5 British TV series Fifth Gear co-starring with Tiff Needell and Vicki Butler-Henderson. He has previously co-presented Channel 4's motoring program 'driven' alongside Mike Brewer and Penny Mallory. He has also competed in the world's tougest touring car races, the Bathurst 1000 and Sandown 500, numerous times but without any great success. His last attempt at Bathurst ended with him causing a crash resulting in John Cleland's car to roll onto it's roof.