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Petrol vs diesel fuel consumption
by Alex
Expert answer:
Quick answer
Diesels generally offer better mpg than equivalent gas engines due to higher thermal efficiency. However, diesel fuel can cost more and produce different emissions.
Detailed answer
Diesel engines operate at higher compression ratios, converting more energy from each liter of fuel. That frequently translates to higher mpg compared to a gas engine of similar displacement. Diesel fuel also has higher energy density. However, some countries price diesel higher, offsetting the mpg advantage.
Emissions differ: diesel can produce fewer CO2 grams per mile but may emit more NOx or particulates without proper aftertreatment. Modern diesels use DPFs and SCR to clean up exhaust. For steady highway driving, diesel’s efficiency often excels. In short city trips, diesel engines might not fully warm up, losing some benefits. Ultimately, the choice depends on fuel costs, usage patterns, and environmental regulations.