Runge Cars Unveils Retro-Inspired R3 Supercar and Air-Cooled V8 Engine

Founded in 2011 by entrepreneur and craftsman Christopher Runge, the Minnesota firm Runge Cars has earned a devoted following among enthusiasts for its hand-built, small-batch restomods inspired by classic Porsche models. Now, the company is stepping into new territory with two bold debuts: the flagship R3 supercar and a brand-new air-cooled, eight-cylinder boxer engine designed to power it.

The naturally aspirated 5.3-liter flat-eight, called Hetzer — a German word that roughly translates to “instigator” or “agitator” — was developed in partnership with the UK’s Swindon Powertrain, a specialist known for building high-performance components for vintage Porsche vehicles.

The Hetzer displaces 5,328 cubic centimeters, runs a 12:1 compression ratio, and features four valves per cylinder with quad overhead camshafts. Designed to rev up to an astonishing 10,000 rpm, the engine is expected to produce around 600 horsepower.

As for the car itself, the Runge R3 draws visual inspiration from the late-1960s Porsche 908 race cars and aims to deliver a purely analog driving experience — the kind of visceral connection modern supercars rarely offer. The Hetzer will be paired exclusively with a six-speed manual gearbox and rear-wheel drive. Preliminary specs put the R3’s curb weight at just 1,720 pounds (around 780 kilograms), promising an incredible power-to-weight ratio.

According to Runge, the R3 has been in development for the past seven years, though so far it exists only as a series of design renderings. These early images show a compact, short-tail coupe reminiscent of the Porsche 908 Kurzheck, complete with a tight cockpit, side mirrors mounted on lift-up doors, and a large rear wing for added downforce. A full reveal of the physical car is expected in the coming months.

Interestingly, Runge Cars doesn’t plan to limit the Hetzer engine to its own vehicles. The company will offer it as a standalone crate motor for builders and restomod projects. With external dimensions nearly identical to the air-cooled 3.6-liter flat-six from the Porsche 911 (964 generation) — a favorite among Porsche restorers — the Hetzer should fit easily into existing engine bays without major modifications.

Runge’s latest creations combine classic racing aesthetics, hand-crafted engineering, and modern performance — a rare blend aimed squarely at purists who crave a mechanical, analog connection between driver and machine.