The diesel engine of Kia Sonet is likely to be borrowed from the Seltos, that is, the 1.5-litre diesel. But the brand hasn't revealed its variant list yet. So, we would suggest you to wait for its launch.
Kia Sonet is expected to make use of the Venue’s petrol engines: the 1.2-litre naturally aspirated petrol and the 1.0-litre turbo-petrol. The diesel engine is likely to be borrowed from the Seltos, that is, the 1.5-litre diesel. All these engines are BS6 compliant. The only automatic for the SUV is expected to be the 7-speed DCT with the 1.0-litre turbo-petrol engine.