Speculation about maruti is that the results were good, but lesser then as expected by the media and herd. that is the main reason for it to go down. Other thing is that with this interest rate hike thing, IMO, banks are the one that gain. Cause with increase in interest rates their earning increases. Where as herd is effected economically, as everybody wants to pay the interest as low as possible.
Other thing to keep in mind is that most of the sales in auto sector are done by finance from banks (Cause it puts question to a salaried person(Income Tax) + Middle class individual cant bring that much money in once instance). so increase in the interest rates also reduces the money flow in market. We may think that it doesnt effect in large numbers, but in fact, increase in .50 of interest rate effects the market a long way.