Kei cars (from "kei-jidosha"—'light automobile') are a uniquely Japanese phenomena which began as a tax and insurance break stimulus for the Japanese car industry in the immediate post WWII era and still exists today. Kei regulations only restrict physical size (3.4 m long, 1.48 m wide and 2 m tall), engine displacement (660cc) and power (47kW), so manufacturers have used every square centimetre and stacked it with as many advanced technologies as possible in order to differentiate their vehicles. The top-selling Kei car is Suzuki's Wagon R which offers a DOHC VVT 660cc engine, CVT transmission, engine stop-start, EBD, ABS, plus a very interesting new Viscodrive coupling that provides on-demand AWD capability without electronics or driver intervention. Prices start at under 10 million yen (USD 9100) and the fully optioned Wagon R still comes in at under USD15,000. Maybe we need a similar stimulus based around size and emissions.
he scheme obviously work as most of the manufacturers produce cars in this category that simply bristle with innovation at a very reasonable price. Indeed, pricing against the specification is almost unbelievable in most Western countries.
The 660cc motor in the Wagon R is only allowed by law to produce 47kW, but using VVT the tiny powerplant manages to deliver a whopping 95 nm at 3000 rpm while delivering 23 km per liter fuel economy (55 mpg).
The Viscodrive coupling is a compact and lightweight unit that provides on-demand AWD capability and improved vehicle traction without the need for costly on-board electronics or driver intervention. Additionally, it dampens undesirable driveline noise and vibration, is highly reliable and is designed to be maintenance-free over the complete lifetime.
This well-proven product consists of friction plates submerged in silicone fluid. When the drive (front) axle loses grip the relative speed difference between the plates produces a sheer stress that transfers torque from one plate to the other and redistributes it to the rear axle.