Hi, I recently had a second service carried out on our E320 CDI estate at 31,500 miles. The garage suggested that the air filters might need replacing, so I thought they can't be hard to fit, so I asked them to supply the parts. Each is held in place with four Torix 20 screws, but there is so little space to work in, it took ages. I accessed the lower ones by holding a shortened T20 bit strapped inside a 7mm spanner, which in turn was strapped to a long hack saw blade to get leverage with flexibility. I then used a long screwdriver in the other hand push the T20 into the head of the screw whilst turning the extended spanner. I wasn't expecting them to look like this! Presumably there is a proper tool which the garage uses to do this and I would imagine the fuel economy will improve.