@evil_driver
Bro, you're talking about City-iDSI for sure!
Why not in previous models?
Man, iDSI is an ultimate lean-burn system with complex kinematics & delicate balances, not just a child's play to put in any engine.
This engine has a compression ratio of 10.8:1 ... ... where, they route back those unburnt air-fuel maixture exhaust gases, again, in the intake manifold, it's really a very difficult to attain such a perfect ignition.
Just imagine: they needed to put Drive-By-Wire Throttle & Catalytic Converter in that little car, just because of iDSI