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Restricted to 64 HP by Law, This Is How Mugen Made the Honda S660 Kei Car Spicier

When the government gives you lemons, you make lem... really cool and agile little sports cars.

As an island nation in harmony with nature, Japan understands that space is limited, efficiency is key, and tall people in other countries, like me, will still jam themselves into an ND Miata purely for the joy of driving. With kei cars restricted by law to only 64 horsepower, Mugen had to get creative to make the S660, aka micro-NSX, sportier.

By 2015, Honda also understood that following the Pininfarina-designed Beat’s demise in 1996, its home market deserved a worthy successor in the two-seater kei sports car class. Weighing 1,873 pounds with a manual transmission and just slightly more with an automatic (CVT), the S660 is a mid-engine roadster powered by a somewhat upgraded version of the Honda N-One’s turbocharged 656cc three-cylinder engine.

When paired with a stick shift, this tiny roadster offers 64 horsepower at 6,000 rpm, along with 77 pound-feet of torque available from 2,600 rpm. Honda’s S07A engine redlines at 7,700rpm, which isn’t half bad from a turbocharged three.


With no power upgrades allowed by the government, Honda racing legend Mugen had to apply its expertise to the rest of the vehicle, which meant adding a new aero package, optical enhancements inside and out, and suspension tweaks for the ultimate in kei-car cornering.

Mugen’s new bumpers and side skirts are made of vacuum-formed plastic. There’s also a more aggressive rear spoiler and diffuser, a stainless-steel sport exhaust optionally wrapped in carbon fiber, and Mugen’s own forged alloy wheels measuring 16 inches at the rear and 15 at the front.

Perhaps most importantly, along with those larger lightweight wheels finished in graphite gun metallic, Japanese costumers can also opt for stiffer springs and dampers, as well as Yamaha’s “Performance Dampers,” which are actually clever anti-roll bars.

The Mugen versions of Honda’s S660 roadsters will be available in the pearl colors Star White, Nighthawk Black and French Blue, as well as the base shades of Carnival Yellow Ⅱ and Frame Red. As for the United States, see you at your local JDM importer in 25 years. 

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