i)first extract rar "toyota markx 250g"
ii)open extracted folder
iii)copy "markx" folder into gta 5 location [mods/update/x64/dlcpack] and paste the folder
iv)now go back to "mods" folder then go to this location [mods/update/update.rpf/common/data]
v)now right click on "dlclist.xml" and click on edit
vi)then paste the line
                      <Item>dlcpacks:\markx\</Item>
                                                 