Many of us have been raised to think “MR2" stands for “Mid-Engine, RWD, 2-Seater” or “Midship-Runabout-2-Seater.” In my research, I’ve discovered the truth. I’m here to explain the truth behind the name “MR2" using physics!
With its mid-engine configuration, the MR2 has a much better moment of inertia than most other cars.
In physics, moment of inertia is, according to Wikipedia:
The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid body is a tensor that determines the torque needed for a desired angular acceleration about a rotational axis. It depends on the body’s mass distribution and the axis chosen, with larger moments requiring more torque to change the body’s rotation.
Which is, in essence, the car’s willingness to rotate. It makes the car very capable in the handling department, but this willingness to rotate can be dangerous. It’s partially to blame for the snap-oversteer inherent in the handling of early-model MR2s.
So, with the heavy mass of the engine moved closer to the center of mass of the car (the point about which the car rotates, in this case) a smaller moment of inertia is achieved. The handling benefits are obvious.
As any dedicated car owner would, I set out to calculate the exact moment of inertia (in kg*m^2 or lb*ft^2) of my car.
As I refreshed my memory on the formulas, something stood out:
Allow me to highlight the key expression here: MR^2. Sound familiar?
Could it be a coincidence that this car, built to minimize moment of inertia, has a name that shows up in a majority of moment of inertia calculations??
To the car-buying audience, “Mid-engine, RWD 2-seater” kind of makes sense. In my opinion, it was never the most elegant name for a sportscar.
But from the standpoint of physics, this name is amazingly obvious, and even more amazingly nerdy. It gives me heart that somebody at Toyota had the idea to name the car after a physics expression, of all things.