A new patent filing from Mazda suggests AWD, a three-motor hybrid powertrain, and a gigantic capacitor could all be in play.
The long-awaited replacement for Mazda's late RX-8 sports coupe is coming - or so we've heard for several years now. But what kind of car will it be? While the "RX" nomenclature has historically been reserved for sports cars with Wankel rotary engines in place of a more conventional piston engine, previous rumors had it that the RX-9 would get the Mazda 6's incoming new inline-six. Still others maintained that it would have a rotary, but that said rotary would serve as nothing more than an onboard generator for what was otherwise a purely electric powertrain.
The truth, it seems, could lie somewhere in-between - at least if a recent patent filing is to be believed.
The filing, discovered by Japanese outlet T's Media, describes a hybrid AWD system with a pair of wheel-hub-mounted electric motors driving the front wheels, and a third 35-kW permanent-magnet motor hanging off the back of the engine. The motors rely on a combination of a double-layer capacitor situated on top of the engine, and a small 3.5-kWh lithium-ion battery pack.
Capacitors tend to favor quick and efficient discharge and recharge cycles, but they don't generally offer the same sort of long-term, high-capacity storage as lithium-ion. The combination of both could allow Mazda to have its cake and eat it, too, delivering immediate power and efficient recharging under braking from the capacitor, with plenty of capacity for sustained low-emissions motoring from the battery pack.
Another key detail laid out in the patent is a rear-mounted transaxle - that is, a transmission and differential combined within the same housing - like the sort of setup used by some front-engine Ferraris and Porsches, not to mention Chevrolet Corvettes from the C5 through the C7. Putting the weight of the transmission at the rear of the car gives it better front-to-rear weight distribution for improved handling.
And a couple of different options for internal combustion engine are presented by the patent filing, as well: a Wankel rotary, and an unidentified V-configuration engine. Both seem almost equally likely, given that neither currently exists anywhere in Mazda's lineup. Nor do the rear transaxle, hub motors, or anything else detailed therein, for that matter.
Of course, just because Mazda has filed to patent the powertrain does not mean it will ever materialize in a production road car. If it does, the Mazda RX-9 could be a sports coupe worth waiting for.