The cars we drive today were influenced by these pioneers. Here we take a look at the world’s first production turbodiesel model.
When Rudolph Diesel developed his eponymous engine in the 1890s, its weight and displacement limited its application to large vehicles such as ships and submarines. Only in 1908 when companies had poured resources into downsizing his original design, did the first diesel-engined truck hit the road.
Despite its greater efficiency, diesels took a back seat to the more refined and – at the time more mechanically predictable – petrol engine, which seemed set to grow in displacement largely unchecked until the 1973 oil crisis saw its application in passenger vehicles reassessed.
Following a year of OPEC-enforced embargoes worldwide, the resultant 300% increase in the price of a barrel of oil meant the days of large sedans with lazy V8s were numbered. Carmakers began downsizing and diesel became a viable means of overcoming this worrisome development.While the market shift to smaller vehicles was a monumental challenge, the task of repackaging diesels from their noisy, commercial applications to something folks would be happy to have powering their daily drives was another matter.
The main impediment was underwhelming performance, something Mercedes-Benz was all too aware of when it decided to turbocharge its slow but impressively bulletproof OM617 D30 inline-five diesel engine.
The upshot of this development was the North American market unveiling of the 300SD in 1978 as the first production-series turbodiesel passenger car. The fuel savings over the D30 were incremental – 10,60 L/100 km versus the naturally aspirated unit’s 10,80 – but the performance gains were substantial. Power rose from a lowly 59 kW/172 N.m to 85 kW/227 N.m, meaning the 0-100 km/h sprint time was pared down from a tectonic 18 seconds to a glacial 15,5. The top speed also took a hike from the D30’s 148 km/h to a slightly handier 165 km/h.
A total of 28 634 examples of the 300SD turbodiesel models were sold between 1978 and 1980, with a more powerful version of the OM617 making a US market-only return in the W126 S-Class before bowing out to the direct injection OM602 in 1985.
Large and relatively cumbersome, these early units played a significant role in moving diesel out of the industrial bracket and into the motoring mainstream. Hybrids and EVs may be touted as the future, but developments such as start-stop ignition systems and improved thermal management mean the oil burner still has some life left in it, yet.
THEY ALSO PAVED THE WAY
1933 Citroën 7U Rosalie
While Mercedes will claim the 1936 260D was the first production-series diesel engined car, it was in fact pipped at the post by Citroën’s 1933 Traction-based 7U Rosalie and its optional 1,7-litre, four-cylinder unit.
1986 BMW E28 524TD
The first passenger car to feature an electrically controlled injection pump. The Bosch-developed system replaced the mechanically weighted distributor, improving both cold starting and cruising speed efficiency.
1997 Alfa Romeo 156 2,4 JTD
The 156 would become the first production passenger vehicle to feature common rail diesel injection. Providing improved fuel vaporisation to boost combustion efficiency, this system saw the 156 turbodiesel model return an impressive 6,70 L/100 km.
2008 Subaru Outback 2,0D
Subaru’s EE engine would be the first horizontally opposed diesel to enter production. In addition to the compact packaging and lower centre of gravity afforded by this layout, the mechanical balance of the boxer made it a refined diesel.