hmm upon closer observation the front bars have their sizes written, 20mm 21 mm and 21.5mm but the rears are still a mystery...

can anyone clarify?

I just found a reference to four different factory sway bars (aren't they anti-sway bars?) at http://www.swedishautoparts.com/850/Volvo-850-suspension-rear.html.

Scroll all the way down to the bottom. If someone can tell me where to look for the mark (M,N, P, or V), I may be able to find it on my ...

Volvo 850 turbo 5 speed with 240K Km
hwy it gets around 8.5L/100km (27.7 MPG)
city it gets around 11.5L/100Km (20.5 MPG)

and it seems a bit slow...