We have heard almost constant rumors of a tie-up between Mercedes-Benz and BMW for the last few years. As market conditions change and German automaker Porsche (via Audi via Volkswagen) pushes forward with its plans for world domination, the two high-end marques have been speaking about the possibility of jointly developing certain pieces of their vehicles. The latest reports specifically mention engines as a project the two Teutonic giants have considered partnering up on. Mercedes' latest direct injection twin turbo V12 is an intriguing prospect for BMW and its Roll Royce brand. Also under discussions are smaller, lower-profit cars that use four-cylinder engines, which BMW has plenty of and Mercedes-Benz does not. The two competitors could swap technology, cutting research and development costs drastically in the process. Or, maybe not. It seems that Daimler is a bit wary of siding with its longtime enemy from across the country. Whatever happens, Car Magazine Online is reporting that BMW is looking to make a deal sometime before the end of the year.