You misunderstoof my post Mehran. The reason low-floor busses are not suitable or more appropriate "preferred" for extended travel is.
1)Most conventional busses carry 500plus liter tanks of USEABLE fuel namely buses servicing the Rawalpindi to karachi routes. Because of a low floor, fuel tanks have to be mounted nearer to the rear of the bus hence further complicating the already gagged setup, There has been improvement in this with the advent of the STEPPED floor busses (gradual increase in height of floor towards the rear but althouugh that accounts for the range the praticality still is not addressed
WHY?
Because as the floor gets lowered, luggage compartments have to be accordingly displaced to unconventional, less accessible and/or less convenient locations, such as within the roof structure (typically between the ceiling panels and the roof skins), or added to an already overcrowded engine compartment.FURTHERMORE, the operational and life cycle of a low floored bus is less then that of a conventional bus.