Saif bhai, what you are referring to is section 231B of Income Tax Ordinance, 2001, Advance tax on purchase, registration and transfer of motor vehicles, which clearly mentions in its proviso as follows:
Provided that the provisions of this section shall not be applicable in the case of –
(a) the Federal Government;
(b) the Provincial Government;
(c) the Local Government;
(d) a foreign diplomat; or
(e) a diplomatic mission in Pakistan.]
A bank, being a listed public company, would therefore be required to pay WHT on purchase/transfer depending upon its income tax active status (Filer/non-filer).
Your second question refers to sub-section 2 of section 231B, the pertinent part of which is being reproduced as under:
The tax to be collected on transfer of vehicles shall be reduced by 10 percent each year from the date of first registration in Pakistan and there will be no collection of tax on transfer of vehicles after five years from the date of first registration in Pakistan.
Hope this answers both questions.