Well the little knowledge that i have is as below:
You can get a maximum of 50% depreciation on the value of your car that you are importing
Value of car means the actual sales price at the time the care was first registered + any additional feature cost + the shipping (this value is called CIF)
Depreciation is calculated as 1% per month from number of months between import to manufacturing (No tax advantage in importing cars over 50 months that is 4 years 2 months so for all u ppl out there u should import calls that were made in Jan 2008 to get the max tax advantage)
there are a few charges on the CIF value for example landing fee of 1% and local admin charges that are almost 5% of CIF (Lets call it AV= the actual value of car)
Now subtract the % age of depreciation from the AV and u have TV = the taxable value of car .
Now for people who are importing 800 to 1000 CC the taxes will be around 92% of the TV
Now for people who are importing 1001 to 1500 CC the taxes will be around 98% of the TV
For People importing 1501-1800 CC it is 117% of the TV
however these are my understanding from the tax documents issued by the FBR