Confusingly, the transmissions in both cars are called Hydra-Matic, but they are not the same transmission, nor are they the same as the original Hydra-Matic introduced back in 1940. The 1960 Oldsmobile 98 uses the four-speed, dual-coupling Hydramatic, introduced in 1956 and shared by Pontiac and Cadillac. The dual-coupling Hydramatic was far more flexible than many two- and three-speed rivals, but it was bulky, enormously complicated, and expensive to produce. The 1961 Oldsmobile uses the new, greatly simplified Roto Hydra-Matic. Although the newer transmission has only three speeds, it uses a torque converter in place of the four-speed’s fluid coupling, giving the effect of an additional gear at very low speeds. The Roto Hydra-Matic (often called “Slim Jim” because of its smaller case) was 75 pounds (34 kg) lighter than its predecessor and a lot cheaper to produce. Unfortunately, it wasn’t very efficient and it had a propensity for fluid leaks, so it was not necessarily an improvement.