speedo

Etymology 1

Abbreviation of speedometer.

noun

1. (informal) A speedometer, particularly one in a race car or other automobile.
   You don′t need to change dashboards since the switches and instruments are suited to the V8, although the speedo and tachometer will require modification to adjust them to your V8′s gearing and cylinders. 2006, Roger Williams, How to Give your MGB V-8 Power, page 209
   One further advantage of the ‘J’ type overdrive units is that the speedo drive gear on the rear drive shaft of the gearbox can be changed, thereby adjusting the speedo-drive ratio to suit the TR′s 15in wheels. 2009, Roger Williams, How to Restore Triumph TR2, 3, 3A, 4 & 4A, page 126
   The main instruments are in the centre of the dash, finished in silver (grey on the GP); consisting of a circular speedo with petrol and temperature gauges on either side. 2012, Martyn Collins, The New Mini: All Models 2001 to 2006, page 34

Etymology 2

noun

1. Alternative letter-case form of Speedo