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A big part of diesel's fuel efficiency advantage is caused by the emissions controls on gasoline powered vehicles. Vehicles from the early 70s often had simila
by LordKano 10y ago
A big part of diesel's fuel efficiency advantage is caused by the emissions controls on gasoline powered vehicles.
Vehicles from the early 70s often had similar gas mileage to smaller lighter vehicles from the late 90s-early 2000s but the newer cars had much better emissions.
If the makers of gasoline powered cars had cheated like VW did on their diesels, the diesel advantage would have been nonexistent.
- bluGill 10y agoEven if you had no emissions laws diesel would still have a large fuel consumption advantage. Diesel contains more energy per volume (139000 btu/gallon vs 124000 btu/gallon). In addition the design of a diesel engine does not require a strict stoichiometric air/fuel ration. The result is at less than full throttle the gasoline engine the efficiency of a gasoline engine drops off faster than a diesel engine. In an ideal efficiency engine (no emissions) a gasoline engine at full throttle is more fuel efferent than a diesel engine, but when at less than full throttle - which is where most engine spend all their time) the diesel engine is more efficient. Note I skipped a dozen pages of disclaimers on the above claim: there are many ways in the real world to cheat the above.
- hx87 10y ago> Vehicles from the early 70s often had similar gas mileage to smaller lighter vehicles from the late 90s-early 2000s but the newer cars had much better emissions. Source? Electronic fuel injection with closed-loop fuel/air control wasn't a mature technology in the 1970s, and open-loop fuel injection (not to mention carburetors) combined with 3- and 4-speed transmissions are inherently less efficient then closed-loop with 4, 5 and 6-speed transmissions.