After Maruti Suzuki, auto major Tata Motors has formally said that it could phase out small diesel cars from its portfolio as demand is expected to slow down after the implementation of the new BS-VI emission norms. This is primarily on account of the fitments needed for the transition making vehicles prohibitively expensive. Maruti Suzuki had earlier stated that it would discontinue diesel models from April 1, 2020, when the BS-VI norms take effect. Affected models Tata Motors currently sells its entry-level hatchback Tiago with 1-litre diesel engine, compact sedan Tigor with 1.05-litre powertrain and older models like the Bolt and the Zest with a 1.3-litre diesel engine. Tata Motors president passenger vehicles business unit Mayank Pareek was quoted by PTI as saying that the "low demand for entry- and mid-size diesel models will not justify the high costs involved in developing a new small capacity engine". Unviability The decision by the Government to leapfrog directly from BS-IV to BS-VI is what carmakers cite as the reason for the unviability of diesel. While petrol vehicles would also need upgrades to transition, these are limited to catalysts and electronic control upgrades. For diesel vehicles, the upgrades are more complicated and entail higher costs, apart from the technical difficulties in managing the changes. Carmakers would have to put three pieces of equipment — a DPF (diesel particulate filter), an SCR (selective catalytic reduction) system, and an LNT (Lean NOx trap) — to meet stringent BS-VI norms, all at the same time. This is vital to curb both PM (particulate matter) and NOx (nitrogen oxides) emissions as mandated under the BS-VI norms. Ideally, the technologies should be introduced in series, and then synergised. A step-by-step transition would have been easier; now, the entire cost will have to be borne in one go, alongside the operational difficulties of managing the transition. Cost impact The economics of the conversion does not make it worthwhile to continue with the diesel option after the transition to BS-VI. The difference in the price of petrol and a diesel car, now around Rs 1 lakh on average, could go up to Rs 2.5 lakh. Also, the sentiment for diesel is not good in the wake of the Volkswagen emissions scandal, making it extra uncertain if customers would want to pay the big premium
