The court also confirmed the Central Bureau of Investigation (CBI) Special Court 2010 ruling of two-year jail for three others in the case.
In 1994, Mr Natarajan imported a new Lexus car forging the papers to show that it made in 1993 and thus evaded a duty of over Rs 1.6 crore.
The CBI had registered a case against Natarajan, his nephew V Baskaran, Balakrishnan, his son Yogesh Balakrishnan and two officials of the Indian Bank, of which one turned approver.
With Balakrishnan on the run, the case was proceeded against the remaining four who were convicted by the CBI court. They moved the Madras High Court against it.
Income Tax officials recently searched the premises of Mr Natarajan for tax evasion.