Sounds about right
Standard GS I assume?
170 to reserve light on, then around 40 - 50 on reserve
How many litres do you put in for your 170 miles?
From nearly empty to brim-full I can fit almost 21 litres into mine
At around 50 mpg this gives me around 220 miles, although I normally fill up at about 210 - usually about 20.3 litres (regular commuter in case you think I'm unduly sad)
G