What puzzles me here is, the centrally mounted speedos are generally seen on old cars, weirdmobiles and/or very cheap cars where optimization has taken that route. Also on modern cars, predominantly, the placement of the central speedo is on the dash, not in front of the dash like on Model 3 - or there is a secondary digital speedo behind the steering wheel like on the Mini Cooper.
I wonder, if a central speedo is such a great idea, why this hasn't taken hold more?
By the way, tried what JRP3 suggested on my Model X and absolutely hated it. The speedo seemed to be too close and too right. Had it been on top of the dash like on a Prius, that could have worked (but on the Model 3 it is not).