Diesel turbo lag is a reality. Car manufacturers world over are trying hard to make power delivery smooth and linear over the entire rpm range even in a diesel car. And Yes Ertiga too depicts a certain amount of diesel lag.
Diesel Lag in Ertiga
Diesel lag in cars is quite prevelant in turbocharged diesel engines irrespective of who the engine manufacturer is. Various efforts and R&D spends are already allocated to reduce this key problem area in case of turbocharged diesel engines.
Ertiga diesel too suffers from this issues, as a matter of fact the lag below 2000 rpm is quite prominent and makes frequent down shifting of gears quite a necessiy in stop and go city traffic. Once threshold rpm is crossed, Ertiga depicts a strong diesel kick, which could make things quite difficult in tight city traffic. For those not habitual of driving a diesel car with a prominent lag and kick, can definitely be taken by surprise. Indigo Manza is another car which behaves quite similarly to the Ertiga in this area.
On the highways, however, Ertiga is a different story as one tend sto drive in an aroudn 2000 ro 2500 Rpm, that's when the car has turbo working thus giving it a very good mid range driving behaviour.