Five-Point Inspection: Mahle Downsizing Demonstrator

Craig Cole
by Craig Cole

In decades past, automakers produced more powerful engines by adding cylinders. As the old saying goes, there’s no replacement for displacement… Or is there?

Case in point: Chevrolet and Ford. In 1929 Chevy dealt a severe blow to old Henry’s popular Model A by introducing a six-cylinder engine that was very similar in price to the four-banger Ford. A few years later the Blue Oval would trump the Bowtie by debuting the world’s first mass-produced V8 in 1932.

Surely this is not the first example of a “horsepower race” but it’s one of the most memorable. It also helped start a trend that ultimately culminated in iconic muscle cars of the 1960s, some of which were powered by monstrous engines approaching – and in some instances exceeding – 500 cubic inches!

But ground-pounding V8s have essentially gone the way of the Apatosaurus, replaced by rev-happy sixes and high-tech four-cylinders. Fuel-economy demands have forced this change. Today automakers are taking downsizing to an extreme. By relying on advanced technologies like direct injection and turbocharging they’re introducing tiny engines that put out serious power. One such example is the so-called “Downsizing Demonstrator” produced by German supplier company Mahle.

To prove what the company is capable of engineers designed and constructed a 1.2-liter three-cylinder engine. The goal was to build a powerplant that’s roughly 50 percent smaller than many of today’s ICEs but with greater fuel economy and no sacrifice in performance.

Mahle’s three-banger is aggressively turbocharged and features centrally mounted direct-fuel injectors as well as four-valve heads with specially optimized combustion chambers. It delivers about 160 horsepower and roughly 210 lb-ft of torque. It’s mounted in a standard-issue, Euro-spec Volkswagen Passat station wagon and is matched to a six-speed manual transmission.

Why three cylinders? Well, for small displacement engines this particular layout is more thermally efficient than a four-banger. Interestingly its output numbers are all over the Passat’s standard-issue 1.8-turbo. The three-cylinder weighs just 125 kilograms, roughly 275 pounds, which is feather-weight for an automotive engine.

Mahle targeted a zero to 60 time of 10 seconds with this car, a goal they beat rather easily. It makes the cut in just 8.9 seconds while delivering a consumption score of 5.8 liters per 100 kilometers on the New European Driving Cycle (NEDC). That works out to nearly 41 miles per gallon, though the U.S. EPA’s test would probably result in a drastically different number. Still, those figures are damn impressive for a 3,500-pound grocery-getter.

Carbon emissions are a big deal in Europe and the Downsizing Demonstrator also performs well in this area, clocking in at about 135 grams per click. Who says you need diesel to get massive fuel-economy figures?

Since this engine only displaces 1.2 liters, vibration-canceling balance shafts are not necessary. Larger powerplants with more internal mass require these parts to keep them from shaking like a shiatsu massager.

All told the Downsizing Demonstrator is quite refined for a non-production engineering test mule. Some vibration does percolate through the engine mounts and into the passenger compartment but it’s no worse than other engines on the market today. An added bonus is the inline-three’s firing interval, which makes it sound quite like a small V6.

The Downsizing demonstrator met Mahle’s fuel-economy and acceleration targets but how does it perform in the real world? In short, very well.

Once underway the car pulls quite strongly up top. The engine is in the meat of its powerband from roughly 1,200 rpm on up. Once the reciprocating bits are moving at a decent clip and the turbo is fully spooled, the car pulls about like a 2.0-liter naturally aspirated four-cylinder. Think of a new Ford Focus and you’ll have a good idea of what it’s like, totally livable and very economical.

One area where it fell short though was in low-end torque. The engine was quite soft just off idle, which made taking off a bit of a challenge. Getting underway required more revs on the clock than typically necessary in most vehicles with a manual transmission. This is something that would almost definitely have a detrimental effect on clutch life, especially if it were driven in hilly terrain or dense stop-and-go traffic.

The car’s transmission is a standard-issue six-speed manual that came in the Passat; it hasn’t been modified in any way. It could probably be made to perform even better if the ratios were optimized to the engine. Additionally the powertrain-control computer’s tuning was not quite 100 percent yet. More work could be done to improve performance with an optimized program.

The Mahle Downsizing Demonstrator is an impressive piece of engineering that clearly and effectively proves the company’s capabilities. It delivers remarkable performance and even better fuel economy.

With a small amount of detail work this engine could be ready for mass production. But company representatives say there are no plans to build or sell it; it’s simply an engineering exercise. That’s too bad because it’s a pretty compelling piece of work and a prescient glimpse of what’s to come in the future. Believe it or not there actually is a replacement for displacement. It’s called technology.

Craig Cole
Craig Cole

Born and raised in metro Detroit, Craig was steeped in mechanics from childhood. He feels as much at home with a wrench or welding gun in his hand as he does behind the wheel or in front of a camera. Putting his Bachelor's Degree in Journalism to good use, he's always pumping out videos, reviews, and features for AutoGuide.com. When the workday is over, he can be found out driving his fully restored 1936 Ford V8 sedan. Craig has covered the automotive industry full time for more than 10 years and is a member of the Automotive Press Association (APA) and Midwest Automotive Media Association (MAMA).

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