Four teams of brilliant bodgers have just six weeks and £1,500 to buy and build roadworthy road hogs to travel the length and breadth of Britain. The cars will also need to be readily convertible to face a series of challenges. The first test is proving their hog is truly roadworthy and then racing head-to-head to decide who'll take the early top spot on the leader-board. The judge Peter Lambert is the man who examines the examiners of the SVA (Single Vehicle Approval) test. The SVA makes sure that new or substantially modified vehicles are safe to drive on British roads. Peter is a talented engineer in his own right, having built a number of road-goers himself. He is also a lover of motorbikes and steam engines.

This week, our teams are travelling 100 miles from the start line in Suffolk to 11th-century Rockingham Castle in Northamptonshire. Waiting for them is an appointment with a giant archery circuit. We're providing the arrows but the teams will be building the bows, which they have to attach to their radical roadsters. In order to succeed against our three intimidating medieval targets, our teams need to build some seriously strapping siege engines.

Our teams have a mountain to climb in this week's Scrappy Races. They have just eight hours to tweak their street-legal roadsters into vertigo-inducing hill climbers that can race up a precipitous one-in-two hill in the Yorkshire Dales. As they come into the contest, Knuckleheadz are neck and neck with reigning champions Chaos Crew as they scale the leader-board. But Cops and Bodgers and the Tartan Starlets are right behind them, looking for their first wins.

This week we're on the banks of the River Tyne where our intrepid bodgers have to convert their roadworthy road hogs into ice cool fire trucks. Our extinguished guests have just eight hours in a Newcastle scrapyard to fabricate and forge their way to becoming the winners this week. There's everything to play for as the Knuckleheadz are only a point behind leaders Chaos Crew and a win for either Cops & Bodgers or Tartan Starlets could lift them right up the leader-board.

Our bold bodgers are nearing the end of their 1,000-mile odyssey. Today, our super scrappers must turn their weary wheels into bog-busting, border-breaking Mud Runners as they race through a maze of deep and dangerous muddy moats and across the finish line into Scotland. Reigning champions the Chaos Crew are neck and neck with the Knuckleheadz on the championship table but the competition is wide open because the vehicles must cross the finish line to be in contention for the Scrappy Races title. First the teams must head for a local scrapyard full of useful old junk, where they have just eight hours to repair, reshape and refine their scrappy racers one final time