New car buying help

Please help me selecting from these options. I have a budget of about 50 to 70 lakhs and selected products are GLC300 petrol and X3 Petrol. I am confused whether to buy a petrol model now r wait until the implementation of BS6 models. Dealers r giving good discounts in GLC 300 at present .
You are also free to suggest any other best option if you think in that price range.