As far as I can recall the Maruti Suzuki Ciaz 2019 was the first to receive the company's then brand new 1.5-liter diesel engine. With that, the 1.3 DDiS engine was discontinued and the new engine was also said to significantly improve the performance. The earlier 1.3-liter petrol engine was quite outdated. This new diesel engine was also said to be BS6 compliant.
However, with the onset of the year 2020, let's look forward to the new Ciaz that will be launched with the new hybrid technology which will not only give better fuel efficiency but will also significantly lower carbon emissions.