August 19th, 2010 
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Since Volkswagen’s little oil-burner can trump Honda’s latest in hybrid tech, how about we up the ante and compare a quattroporte version with the world’s most notorious gasoline scrooge, the hyper-hybrid Prius? At a combined EPA rating of 50 mpg (FYI, 93 Prius owners are currently reporting an average of 48.8 mpg at www.fueleconomy.org), the Prius runs away with the mpg facet of this contest. By contrast, our TDI offers an impressive — but in this lofty company, comparably feeble — 34 combined EPA mpg. Recomputed the way it ought to be, as gallons per 100 miles, the Prius requires 2.0 gallons to cover a Benja-mile, the Golf, 2.94, or 47 percent greater consumption per mile. As Queen Victoria was gently (and probably apocryphally) answered while watching the yacht America run away with the Hundred Guinea Cup race in 1851 (today’s America’s Cup), “Your majesty, there is no second.”
And it gets worse. Just about nobody seems to realize that diesel’s longer-chain hydrocarbons silently provide it with about 11 percent more energy per gallon than gasoline (it’s heavier by about that too). In other words, when comparing diesel and gasoline engines, a diesel’s first 11 percent (or thereabouts) of its 30-40-percent-greater efficiency ought to be discounted simply due to its denser energy content.
Before you speed-type me those flame mails, I’ve now read about 312 breathless tales from diesel drivers asserting things like they just got 70 mpg (nay, 85 mpg!) on the way back from Aunt Margaret’s in Bakersfield. Last year we carefully logged a long-term Jetta TDI for 20,000 real-world miles and it returned…(snarl-roll)…34.8 mpg (rim-shot). Not bad actually: Its EPA combined figure was 33.1 mpg. Perhaps miracles do happen, but on any particular drive you take, a zephyr of a tail breeze, or an imperceptible grade can starkly affect any individual outcome. Of course, it’s the good runs that get remembered.
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