Model B. The engine was a flat-twin design with two valves per cylinder. The engine was very successful for Buick, with the company selling 750 such cars in 1905. Several other manufacturers began to produce OHV engines, such as the 1906–1912 Wright Brothers Vertical 4-Cylinder Engine. In 1911, Chevrolet joined Buick in almost exclusive use of OHV engines. However, side-valve engines remained commonplace until the late 1940s, when they began to be phased out for OHV engines. Overhead camshaft engines The first overhead camshaft (OHC) engine dates back to 1902, however use of this design was mostly limited to high performance cars for many decades. OHC engines slowly became more common from the 1950s to the 1990s, and by the start of the 21st century, the majority of automotive engines (except for some North American V8 engines) used an OHC design. At the 1994 Indianapolis 500 motor race, Team Penske entered a car powered by the custom-built Mercedes-Benz 500I pushrod engine. Due to a loophole in the rules, the pushrod engine was allowed to use a larger displacement and higher boost pressure, significantly increasing its power output compared to the OHC engines used by other teams. Team Penske qualified in pole position and won the race by a large margin. In the early 21st century, several pushrod V8 engines from General Motors and Chrysler used variable displacement to reduce fuel consumption and exhaust emissions. In 2008, the first production pushrod engine to use variable valve timing was introduced in the Dodge Viper (fourth generation). Design OHV engines have several advantages compared with OHC engines: Smaller overall packaging: The cam-in-block design of an OHV engine results in a smaller overall size, compared with an equivalent OHC engine. Using the same cylinder head casting for both cylinder banks: A V-type engine design allows both cylinder heads to be mirror images of each other at the front of each cylinder bank. In a V-type OHV engine design it is possible to use the same cylinder head casting for both banks, by simply flipping it around for the second bank. General Motors LS-based small-block engine family is a popular example of these kind of OHV V-engines. Simpler camshaft drive system: OHV engines have a less complex drive system for the camshaft when compared with OHC engines. Most OHC engines drive the camshaft or camshafts using a timing belt, a chain, or multiple chains. These