The four-cylinder Model D was introduced in 1905 which brought significant improvements in power and performance to the Cadillac line of vehicles. Regardless, the single-cylinder models remained in production, and popularity, through 1908. The single-cylinder engines were durable and adequate, proven by their popularity and in endurance runs. Three Model K Cadillac's competed in the Dewar competition in England in 1908 and emerged victorious. At the close of the endurance run, all three cars were disassembled and their parts scrambled. The cars were then re-assembled from the mix-matched parts and easily started. This final demonstration was to reinforce Leland's precision manufacture and to the slogan 'The Standard of the World.'
A design change was added in 1905, following the popular configuration of the time. The front was given a dummy hood over the front axle while the engine remained under the seats. In the front was a vertical radiator on the Models C, E, and F. These were replaced for 1906 by Models K and M. Both of the K and M were identical except for the Model M having a wheelbase two inches longer. Production of the K and M continued into 1907. In 1907 the Model S and T were introduced, with the T remaining in production until the end of 1908. By Daniel Vaughan | May 2012