Further evolving the successful GR51, the GR55 won 5 straight championships in one of two forms, winning every round of the 2006 British Hill Climb Championship.
The GR55 and GR55B took further steps in achieving a lighter weight race car, with the latter shaving an additional 25 kilograms from the original despite seeing a larger capacity engine.
With an all-new chassis construction to aid the weight loss, the rear suspension was redesigned to use a third spring setup, mounted on the gearbox casing to aid the control of ride height and downforce levels at speed.
Adam won the championship in 2003 and 2004 in his 3300cc V8 Nicholson McLaren Engine'd GR55, before retiring from the series to focus on other commitments.
Adam's second season in the car came in 2003, where he entered 28 of the 34 races, winning 11 in total and scoring a podium in 92% of races. Wight Jr came a close second place, but with Fleetwood becoming ever more comfortable behind the wheel of the GR55 he was sure to improve further.
And he did. The 2004 Championship was Fleetwood's for the taking. Entering 31 rounds and winning 28 set a new record for the series, not to mention breaking all but one hill record on the calendar in the process, imprinting his name in the history books and leaving others to wonder what could have followed.
Martin set a new standard for British hill climb racing, with four Championships to his name and three in succession from 2005 to 2007, he fought hard with Scott Moran in the newer GR61X to reclaim the title in 2010.
In the lighter, 3500cc V8 Nicholson McLaren Engine GR55B, Groves dominated the 2005 season to win 24 rounds out of an entered 32, placing on the podium in every event to claim victory by over 100 points.
Competition intensified in 2006 and 2007, with Scott Moran erupting on the scene with the GR61X to force hill record points to decide Groves as the winner for the years.
Not one for giving in, Martin kept at the championship, placing 2nd in 2008, 4th in 2009 (missing 12 of the 33 rounds) and won once more to break Moran's winning streak in 2010.