1. If your business model is just being a mediator & car does not get registered in your name (being a middle man) than it wont count as part of your turnover.
What will be part of Turnover??
Ans: Only the fees charged by you will count in Turnover. So kindly sum up the fees & if it exceeds Rs 40 lac then only go for registration.
There is a concept of pure agent, it will apply only in case if you put forward invoice to the purchaser of car from you ( invoice specifically shows that X amount you are collecting on behalf of original car owner & you will reimburse it to original car owner. Then also such amt wont get counted in part of your turnover)
2. If your Income is not on basis of commission & you buy the car at x price & sell at y price without both the parties knowing at what price the other purchase or sell you are doing. Then department may include whole of the amount which you are taking in your bank account as part of your Turnover.
Dear on the reply which you posted their was no link in it.
Question which tax rate is applicable to you. ??
Ans. 1% & 6% is basically a composition scheme for traders & service providers where you pay flat 1 or 6% of your turnover & get no itc. ( least complaince required)
1% is for those whose work is primarily trading & involves no service component. ( Now post your buynig of car if you are also doing repairing & up gradation work & then you are selling, in that case since service component is involved you need to opt for 6% -service composition. If it pure buying & selling without any service component than it will be straight forward 1% composition.
Second option : Opt for regular scheme where you pay the taxes at 18% of your turnover value & can claim the credit for the input.