A/C on with 5 people+luggage while climbing isn't an issue with 75 HP. Obviously it won't equate to a single occupant's situation & will sound less relaxed but it's a very capable machine. It's rather easy for MJD, i would say. What better way to conclude that it's mileage will hardly drop by 1 km/ltr with all that extra load & A/C on. It's not working that extra hard that total added weight seems to portray. It's state of the art & very advanced engine so not surprised for Ambassador diesel at all. Such cars are in-fact dangerous in Ghats when overloaded. Reason is with less power, if some has to stop at steep inclination & loose inertia, they may start rolling back & situation can get out of hands. I have heard that a lot in old diesel vehicles & especially bus/trucks. Is that swift is petrol one? Diesel shouldn't face this issue at all else there could be something wrong with maintenance of swift. These engines come out flying colours in toughest situation imaginable.