Car is a 07 plate (06 manufacture) 1.8 focus ghia. On checking as many websites as I can, they all list bosch super plus +39 or super 4 521 as suitable. These have a 25mm length thread. Other plugs listed, eg denso, also have a 25mm thread. However, upon purchasing a set of bosch from Halfords (also correct for the car's reg on their database), they are longer than the plugs in the car (original FoMoCo parts). Went to the main dealer, and the plugs they have in stock for the car are the same (17.5mm length thread) as the car has fitted. Went to local autocentre, who list a bosch plug (HR8DPP15V) for the car that on doing an internet search only fits a 2.5 V6 Mondeo. They also list an NGK (ITR6F13) that is also listed for the 1.8 Focus MK2 on the NGK website, but surprise surprise at least one website lists this option for the focus alongside the longer Bosch and denso. There does seem to be agreement that the longer plug fits the 1.4 and 1.6 models. I tried one of the longer Bosch in the car (All plugs out, checking rotation past TDC with a screwdriver in the adjacent bore) having popped a dob of blutack on the plug nose, and rotating the engine by hand. It went round without obstruction, and on inspecting the plug it had about 2mm clearance between the plug nose and piston crown, but I didn't have the nerve to fit all four and fire the engine up. So..... any ideas whether the longer Bosch etc. are suitable? I wouldn't be so bothered if it wasn't for the fact that the car seems a little underpowered to me for a 1.8, and fuel consumption is worse than I had hoped - 27 round town 40 on a motorway at steady 70mph.