Dan Neil:

From Ford to Ferrari, Audi to Volvo, auto makers are being obliged to move to smaller, forced-induction engines to make power while still lowering emissions. As they do, the character, the sinew, even the sound of performance is changing. And nowhere is the effect more striking than in the Ford Mustang, with its 2.3-liter EcoBoost engine. It’s kind of the New Fast.
 
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 Is that a lot? Historically, it’s huge. Let’s flip open the Big Book of Mustang History and put our finger on… Here we go: The 1971 Boss 351’s “Cleveland” four-barrel V8 put out 330 All-American horsepower, 370 pound-feet of torque, and all the hydrocarbons you could choke on (visual aid: the “Eleanor” in Hollywood’s original 1974 “Gone in 60 Seconds” was a ‘71 SportsRoof, though not a Boss 351).
 
 This was one of the era’s last monster motors, a piston-powered rock god, a hand-built high-comp 5.7-liter V8 with a big Holley carb, solid-lifter cam, Magnafluxed heads, the works. A four-speed Hurst shifter and 3.91:1 Traction-Lok rear end helped put the Boss 351’s power to the ground in respectable fashion: 0-60 mph in 5.6 seconds and a quarter-mile elapsed-time of 13.9 seconds. All in all, a ground-shaking, tire-baking bit of American mechanical culture, that made an impression on millions.
 
 The gas-sipping Mustang EcoBoost is exactly as quick as beastly Boss 351, within the same 0-60 mph and the quarter-mile times, but using half the number of cylinders and delivering roughly three times the fuel economy (21/32/25 mpg, city/ highway/ combined). This despite the fact that the new Mustang is obliged to carry hundreds of pounds more air bags, computers, catalytic converters and crash structures than the Boss 351 (total=0).