Your red tell tale for 70mph on the speedo makes the point that parallax is a big issue with an instrument so far off the drivers angle of view - it is at about the 65mph mark. To my mind the road speed is so important, that I would be very unhappy with the speedo in that position. I much prefer it straight ahead as in my 2005 4/4 (and presumably your roadster) which gives the best of both worlds as both speedo and tacho are in front of the driver and visible through the steering wheel. Interestingly my speedo is almost exactly accurate by GPS, unlike most cars that read 5-10% over.
Nigel
Nigel, my Roadster has the Speedo and "3 dial cluster" reversed from the layout on Dave's car. So the speedo is reasonably readable.
You are right, by GPS the car speedo is spot on, most unusual as every other car or bike I've owned had a speedo that under read by 5 to 10%.