I have seen many topics on Pakwheels inquiring about importing a car for disabled, well i my self is disabled and i was also searching for the answer of same question. Sadly there is no such way through which a disable person can import a car for himself with discounted duty rates. However there is a Government scheme under which disabled person can buy locally assembled car with some concession.
First here under is the application form for the scheme

this application should be sent to the Mr Awais Abbassi in the Ministry of Commerce(address is at the bottom of app form), after sending of application they will invite you for the interview/assessment by the board. This meeting takes place twice a year but in 2008 due to some reasons it took place only once.
If ur case is successful then you ll get the tax discount under this S.R.O
GOVERNMENT OF PAKISTAN
MINISTRY OF FINANCE AND REVNEUE
(REVENIE DIVISION)
Islamabad,the 14th May,2007.
NOTIFICATION
(CUSTOMS)
S.R.O.395(I)/2007.- In exercise of the powers conferred by section 19 of the Custom sAct,1969 (IV of 1969), the Federal Government is pleased to direct that completely knocked down (CKD) kits and special gadgets to be fitted in the motor vehicle not exceeding 1350 cc cylinder capacity, to over-come disability if imported for the war-disabled defence force personnel or by a civil disabled personnel, shall be exempt from so much of the customs-duty chargeable thereon as is in excess of 10% ad valorem in accordance with the conditions laid down in the Customs General order issued by the Central Board of Revenue.
2. This notificati0n shall be deemed to have taken effect from the 6th day of June,2005
------------------------------------------------------------------------------------------------------------[C.No.1(1)Tar-II/87-20/2007]
(MUSARRAT JABEEN)
Additional Secretary
I dont know exactly how much concesstion there is but for Honda City its about 100k and for Daihatsu Coure its about 70k.
I had applied for this scheme and approved, so if in the near future i didn't counter any severe financial blow, i ll book a honda city in feb under this scheme insha ALLAH.
Thanks.