Perquisite to non-specified employee

Yes it isnt taxable in hands of non specified employee. But you get covered under specified employee if your annual salary is more than 50000 per annum. And practically in todays world you will hardly find any employee earning less than 50000 per annum.

Suppose a Chairperson of a company is provided with a car and driver - how to calculate the perquisite tax?
The Chairperson is not a paid employee - and may not receive remuneration of the order of 50k per year, or any remuneration at all. 
We do know the perquisite value for specified employee would be 1800 + 900 for cars below 1.6L and provided along with driver.
But in this case Chairperson is not a specified employee - how to calculate tax of this perquisite for the chairperson?