Waiting for a BS-VI-compliant diesel car

I want to buy a diesel car. Should I wait for one that’s BS-VI compliant or should I just go for a BS-IV-compliant car? What will be the effect of using BS-VI grade fuel in a BS-IV car?
Aashish, Panchkula

AAA BS-VI diesel has a sulphur content of 10 parts per million compared to 50 parts per million of the current BS-IV diesel. This makes BS-VI diesel much more environment friendly. HC and NOx emissions are also reduced by 50 percent, along with a five-fold reduction in particulate matter. However, there are some long-term implications of using BS-VI fuel in a BS-IV vehicle due to the difference in sulphur content and some chemical properties – a result of more complex refinery methods used to make the fuel cleaner. The fuel injectors need sulphur in diesel for chemical lubrication, so due to the lower content, there is a possibility of internal scoring or wear and tear in the long run. However, past experience in other countries has shown that this problem is more theoretical and not a major issue. If your heart is set on a new car, we recommend you go ahead and buy it.