There was a time, not so long ago, when turbocharged diesel technology in passenger cars represented the tip of the efficient internal combustion engine spear. Cars like Volkswagen’s Passat 2.0TDi, on sale in the USA from 2012, had a range of nearly 800 miles on a single tank of low-sulphur diesel, returning around 43 MPG. It doesn’t get much more efficient than that.
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