If I were you, I'd pick the Merc.
Please consider the maintenance costs of both cars as there's a big difference there compared to the fuel consumption of the cars.
You'll save some money buying the Merc but in the long run it's going to be expensive but totally worth the buck.
I don't see what's the problem with naive members having issues with the Poster being concerned about fuel economy, initial cost of the vehicle has got nothing to do with how much money you'll have to throw at it as each day passes by.
Members really need to grow up here, it's a shame there's even such members existing on Pakwheels. Gone are the days when this was a decent forum.
Lastly, it doesn't matter if the Poster's dad is paying for the car or if he himself is paying, answer what he's asking and don't bother with idiotic comments.
Mods, you guys are to be blamed here as well. Start moderating, it's an open forum but at least maintain the quality of responses.