Imagining The Electric Miata – CleanTechnica

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Last Updated on: 29th April 2025, 04:06 pm

The Porsche 911 may the sports car that has been in continuous production the longest, but the Mazda Miata is the best selling roadster of all time. It was originally designed to be a high volume, low cost alternative to the Lotus Elan. Introduced in 1989 at the Chicago Auto Show, it was the embodiment of Colin Chapman’s design philosophy, which was, “Horsepower makes you faster on the straights, but lightness makes you faster everywhere.”

In fact, lightness was a key consideration in designing the Miata. According to Wikipedia, the guiding principle of the original design team was  Jinba ittai (人馬一体), meaning “oneness of horse and rider.” If you are a fan of roadsters, that philosophy perfectly captures the spirit of those cars — light, agile, and thrilling to drive.

Mazda has never been much a leader in the EV Revolution, although it is trying to catch up as best it can. Last week at the Shanghai Auto Show, it introduced the EZ-60 battery-electric SUV manufactured in partnership with Changan. According to Motor 1, in October of 2024, it filed an application with the US Patent Office entitled simply Electric Automobile. In it, Mazda talks about how its design could work in a sedan or other vehicle types, but the description and drawings specifically focus on a small sports car — like the Miata.

Officially, the next generation Miata — known outside the US as the MX-5 — will be powered by a gasoline engine, just as every Miata ever produced has been. A few years ago, the company did broach the idea of a plug-in hybrid powertrain for the car, but nothing ever came of it. The patent application is more of a conceptual exercise. What if the company decided to make the Miata electric? How would it do that?

As the EV revolution has unfolded so far, the vehicles all have had “skateboard” designs that mount the batteries under the floor of the car as close to the road as possible. There are good reasons to do that. Batteries are heavy. The higher above the road that weight is located, the more the vehicle tends to roll in corners. Too much weight, too high up makes for an unstable vehicle.

Some readers may remember when the Tesla Model S first appeared and other automakers were trying to figure out how to build electric cars of their own, a senior engineer at Audi told the press his company would just stuff battery cells into conventional cars wherever there was room — under the hood, in the trunk, under the rear seat, inside the doors and glove box — and connect them all with wires. As my old Irish grandfather liked to say, “Son, that’s an idea. It’s no damn good, but it is an idea.” Since then, the “skateboard” has become the default design choice for virtually every electric car from every manufacturer.

The Mazda Miata & Inertia

Motor 1 says the Mazda patent idea is not to use a big battery in a skateboard design. Instead, it would use multiple layers of cells installed in the middle of the car where the transmission and driveshaft tunnel would normally be. According to the patent, “since the battery is installed in the tunnel portion, the gravity center of the vehicle can be close to the center of the vehicle, thereby reducing the yaw moment of inertia more.”

This keeps the mass centrally located, but it doesn’t stop there. A single electric motor would also be mounted in the tunnel, connecting via a short drive shaft to a rear differential. Per the patent, the principal of putting the motor in the middle of the car is the same as it is for the placement of the battery. “Herein, since the motor overlaps at least part of the back portion of the seat in the side view, the motor comes to be closer to the central portion, in the longitudinal direction, of the vehicle. Thereby, the yaw moment of inertia can be reduced further.”

Not all of us are engineers, but once again, Wikipedia is there to help us understand the arcane principles of physics. It says, “The moment of inertia, otherwise known as the mass moment of inertia, angular/rotational mass, second moment of mass, or most accurately, rotational inertia of a rigid body is defined relative to a rotational axis. It is the ratio between the torque applied and the resulting angular acceleration about that axis.  It plays the same role in rotational motion as mass does in linear motion. A body’s moment of inertia about a particular axis depends both on the mass and its distribution relative to the axis.”

Clear as mud? Think of it this way. Imagine swinging a baseball bat back and forth while standing at the plate and waiting for the pitch. Easy, right? Now imagine that same bat with with a 5-pound weight on the end. Now when you swing the bat, it wants to keep on swinging. Bringing it back the other way is suddenly a lot more difficult. The same principle applies to automobile design.

The more the mass of a car is concentrated near the center, the more agile the car is. Drivers sometimes use the word “flickable” to describe a well balanced car that loves to carve its way through a series of linked S turns at maximum speed. A 1952 Buick Roadmaster with its straight 8 engine mounted far forward in the chassis may have had a lot of “road hugging weight,” but if the road suddenly got curvy, it heaved and bucked like a frigate in a gale — hardily confidence inspiring it you were sawing on the steering wheel, trying to get the beast to turn. That’s why for generations, automotive designers have focused on so-called mid-engine cars like Fiat X 1/9, the Toyota MR2, and the latest Corvette.

The Mazda design in the patent application also allows space for additional battery packs strategically placed further out from the center. It also shows smaller battery packs mounted behind each seat and a battery mounted ahead of the passenger seat to partially offset the weight of the driver. That’s an indication of how seriously Mazda is taking the whole balance thing. Porsche has been having the devil’s own time trying to convert its 718 Cayman and Boxster models to battery power. It’s fairly easy to do when you are talking about a full size SUV or pickup truck, but daunting when talking about small, lithe sports cars.

It seems clear that weight is the enemy. The batteries available today simply weigh too much to fit the sports car motif. But smaller, lighter batteries are under development, which means the idea of an electric Miata may become a reality somewhere down the road. A two-seater roadster with the urgent acceleration of an electric motor sounds like just the thing to keep the Miata mystique going for a new generation of drivers.