The limit of acceleration has been reached. What may well be considered a maximum for practical service has been secured. The present seven-passenger body is as roomy as could be desired. There should be no need for further increase in size. The author believes the total weight of this large car will be reduced to between 3500 to 4000 lb. To make this reduction without sacrifice of durability greater use must be made of alloy steels and aluminum alloys.The tendency in body design and style is toward smoother lines, fewer breaks and a more graceful contour. The number of closed cars is increasing. There will be a general simplification of detail throughout, better wiring, better lubrication, an increased use of oilless bushings and fewer grease-cups. Brakes and wearing parts will be made more accessible and easier of adjustment. The take-up points for the various adjustments will be placed so that they can be reached with ease.In the design of the engine the greatest improvement is to be looked for in the cylinders, valve ports, valve mechanisms, manifolds and carbureters. More heat must be applied to the manifolds. Resistances in manifolds, valve ports and cylinders must be kept as low as possible. The six-cylinder engine will be used for the heavier cars, those of 3500 to 4000 lb., and four-speed transmissions. To provide a quiet drive for maximum speed the silent chain may be used. For the smaller sizes of car four-cylinder engines and three-speed transmissions will suffice. By using a transmission with direct drive on the third speed and a geared-up drive on the fourth, it will be possible to retain low axle ratio and good low-speed performance, and at the same time have the maximum car speed available on the fourth gear. The construction of the transmission as a unit with the engine promises to become the most popular.