Cars Q&A

On 11/10/10 i bought Hyundai i20 CRDI magna. while booking the car i specifically told that i want BS IV version only. at last when i got that car in my hand BSIV sticker was not there in the car and they told its BS IV car only and Hyundai has written that in my RC and sales invoice. even i spoke to Hyundai customer care in phone at that time also they told its BS IV only. my question is if its BSIv then why that sticker is not there in the back glass. is there any way to find out if its BS III or BS IV?