With all due respect to posters.
140Km/hr seems much realistic on petrol without A/C.
My 2005 Civic takes a lot of time to reach 150km/hr ( nearly 50sec or so ), with two people sitting, Petrol, w/O A/C, and its maintained by Honda South.
My 1988 Accord max out at around 190km/hr, High octane, driver only, it has a drag coefficient 30% better then 2005 Civic Eagle Eye and nearly as good as 2009 Civic and weighs nearly 200kg less, and its 1.6L.
I never believed on the speedos of Local cars, I have overtook my cousin's Prosmatec @ 130km/hr in my Accord, while he was swearing that his speedo was showing 150km/hr.
Only the radar gun gives you the correct speed, for your reference a 1.8L 140HP manual civic cant go above 193km/hr (thats 100% true and certified).
I have a 2007 Alto VXR FF CNG.