Possible Clues:

• Mileage displayer
• Car mileage recorder
• Old actor's inwardly satisfied: a measure of how far he has come?
• Device showing a vehicle's distance travelled
• This will show you how far it's been to have tore around the dome
• Dash instrument
• Set in concrete, MOD office backing measure
• O, do see how far you can get with it when you meet her
• Measure of progress satisfied in one making love?
• Old performer encountered coming in with 'lengthy' instrument