See actually Ecosports turbo band is from 1400-4500 rpm the widest band as well, but for Indian version they might have tuned the turbo to come late say by 1800 rpm for fuel economy gains at highway but that dosent mean turbo is OFF until 1800 rpm, turbo spools up the air fuel mixture but dosent burn them efficiently till 1800 rpm, once the turbo is on @1800 rpm the boost pressure stimulates further burning and instant wave of torque will be developed, at about 2000 rpm full 170 NM will be developed,by 1800 maybe just 140 NM will be on tap and below that, that is the 1400-1800 range is really the wastage part here the engine will use more petrol than usual but dosent burn effectively fully due to the tuning of engine for turbo to come late,
The same phenomenon happens in Ford Fiesta 2012 as well, the fiesta has huge turbo lag below 2000 rpm, but same engine in Ecosport has very less turbo lag compared to Fiesta 2012 and even after being 120 kg heavier than Fiesta sedan Ecosport reaches 100 kmph almost in the same time, New Fiesta 0-100 kmph 13.33 s and Ecosport 13.76 s, so it fully depends on how the engine and its turbo zone is tuned, actually according to me Ford has messed up with Ecosport ecoboost tuning, they could have done much better by spooling turbo @1400 and boosting it to full force by just 1500 rpm like in Focus 1.0 ecoboost and Fiesta 1.0 ecoboost in Europe, but to get a big ARAI number in highway Ford might have done this to the Engine of the year