that is bcoz 13bt comes with a turbo so it will naturally gain more speed in less time than the 3b
and about the mileage issue on 12ht i don't know who told u that it'll never give u more than 7km...it wrong...we do have a hj61 and it is givin mileage 10-11km...
i've noticed this that 4x4 owner don't keep their cars to proper tuning level...they won't pay much attention to the engine tune ups
mr rao hamid said his rkr gives him around 4km/l....we had a rkr back in 2008..and it used to give us around 8.km in city and would go to 12km/l on long route...
ppl keep low tire pressures in 4x4 for comfort...which effects a LOT on the mileage,,,
keepin the air filter clean..using original diesel filters, air filters, nozzles, engine oil, even drivin it in the torque range saves lots of fuel...
and i always discuss only those cars which i've driven and tested personally to my best level...i love to tweak and tune a lot...
It is a little vain of you to assume that others don't bother with tune-ups. Just so you know, I regularly off road, and after each trip, everyone at my club typically spends 3-4 days at the workshop trying to get the cuts and bruises and engine tuned up to the way it was before the trip.
I will happily gift you my RKR if you can get 8km/l in a similar vehicle in LAHORE traffic, with the AC on throughout and with a 3f engine. In addition, I am posting a link to another thread where I asked a question regarding consumption, you can see that others have had similar numbers. Haven't tried the long route yet, but I can imagine she will be happier cruising at 80-90 kms/hr in 4 gear than she is in the city in. Check out this thread. I also think your analysis of the 12HT is off, it has been known to have better figures than what you suggest. The same person who gets 4km/lt in a 3F got 8.9 km/lt in Lahore traffic in a 60 series. That is excellent I believe.
Let me know who should tune my 3f without a loss in power and can give me 8km/lt.