the four designs despite their visual similarities, resulting in confusion for owners who naturally assumed that replacement parts would be usable across brands. In addition to these issues and the obvious overlap in production costs, the cost of certifying so many different engines for tightening worldwide emissions regulations threatened to become very costly. Thus, by the early 1980s, GM had consolidated its powertrain engineering efforts into a few distinct lines. Generally, North American and European engineering units remained separate, with Australia's Holden and other global divisions borrowing designs from one or the other as needed. GM also worked out sharing agreements with other manufacturers such as Isuzu and Nissan to fill certain gaps in engineering. Similarly, the company also purchased other automotive firms (including Saab and Daewoo), eventually folding their engine designs into the corporate portfolio as well. GM later reorganized its Powertrain Division into GM Global Propulsion Systems, located at 800 N Glenwood Ave in Pontiac, Michigan, which became the GM Global Product Group in March 2020 and is in close proximity to the old location of Pontiac Assembly. GM's German subsidiary, Opel, relies on a range of three-, four- and six-cylinder gasoline and diesel engines. A survey of their range shows a reliance on petrol and diesel four-cylinders, and in 2014, there was only one 3-cylinder engine and one 6 cylinder engine in service in Opel's passenger car range. In addition to automobile and truck engines, GM produced industrial engines, which were sold by brands such as Detroit Diesel, Allison, and Electro-Motive. Most of these engine designs are unrelated to GM's automotive engines. Automotive gasoline engines Two-cylinder 1904-1911 Buick OHV flat-twin World's first production overhead valve engine. 1909 Oakland vertical engine Three-cylinder Inline-3 1991–present Daewoo M-TEC/S-TEC (acquired with purchase of Daewoo) 1984–present Suzuki G (designed and built by Suzuki) 1996–present GM Family 0 2013–present Small Gasoline Engine 2018–present GM E-Turbo engine Four-cylinder Inline-4 1905-1914 Cadillac Model D side-valve (acquired as part of the founding of GM) 1906-1923 Oldsmobile Model S side-valve (acquired as part of the founding of GM) 1906-1911 Buick Model D inline-4 (T-head design, the only non-OHV Buick engine ever made) 1909–1915, 1917-1918 Buick OHV (Model 10 had OHV-4) 1917-1924 Buick Series 30 OHV inline-4 1909 Oakland Model 40 (acquired as part of the founding of GM) 1913-1928 Chevrolet inline-4 (acquired as part of Chevrolet's merger into GM) 1923 Chevrolet Series M Copper-Cooled 1937-1965 Opel Olympia