Likely to be the downsized version of Tata's 2.2L VARICOR unit.
OD reports that this particular example is testing a new 1.99-litre diesel engine, which is likely to be the downsized version of Tata's 2.2L VARICOR unit. The company was working on introducing a smaller engine in the Safari Store and Tata Hexa while the ban on diesel-powered car displacing over 2000 cc was in effect. On August 13, the Supreme Court lifted the ban and introduced a 1 percent cess on vehicles affected.
Irrespective of that, Tata could still introduce the 1.99L engine as its unclear if the ban will be reinstated at a later time. It had affected sales for manufacturers with vehicles powered by big diesel engines in their portfolio, and should it come into effect again, Tata would at least have a temporary solution ready.
Mahindra is the only manufacturer to come out with the solution of downsizing their bigger diesel engines in products like the Scorpio and XUV500 to tackle the ban. So it's not surprising that Tata is testing the Safari Storme 1.99L against the XUV500 1.99L, as OD reports.