Just replaced the fuel filter and glow plugs on my S320 this evening. Ever since I bought the car a few weeks ago, the glow plug light stayed on for a few minutes after driving. Longer than normal anyway. Also, when the weather turned cold, it took a good bit of cranking to get the car started. Although it always did in the end. I took the opportunity of a free afternoon to get the glow plugs and fuel filter changed. Six Beru glow plugs were around £11 each from ECP plus a Mann fuel filter of around £15. I also got a 10% discount code. First job was to take off the y pipe which leads from the two air boxes and into the turbo intake. Jubilee clips were loosened on each air box and it the turbo I take where the orange seal is. Then the two MAF plugs along with another smaller plug were removed from the piping. This was lifted out. The fuel filter was held in by an Allen key which tightened the cage around it's sides. Once this was loosened and the two fuel pipes popped off, the fuel filter was removed and replaced. Small grey plugs were attached onto the end of each glow plug. These had little push catches on each side which pushed in and then the plugs lifted off. My plugs looked as though they had been done before as they all came out pretty easily. A smear of copper grease on the thread of the new plugs and they were then fitted. All in all, the job took about an hour with the help of my mate (who's a Ferrari technician). The car started first time and the glow plug light no longer stays on. Pretty happy with the work done and the cost of the parts.