You are right to mention that it is too good to be true.
Let me depict the picture of upcoming events in case you went to buy a car from them. They will take your down payment and some other charges and will then ask you to wait until your case is verified and approved by their company. Even after months and years, your case will neither be approved nor will you get your money back. This is how their business model works.
Think it yourself that why will a person/company be willing to provide lease only on 5% interest rate when they can get 20% return on their money from bank. All they have to do is to put their money in the bank.
This is not happening first time with anyone, there are threads on Pakwheels forum where people have lost their money in exactly similar schemes. I will post the link if I find that thread.