Good policy from the government.
Ideally there should be HSR between major division level cities, like Dhaka, Chittagong, Sylhet, Rajshahi, Barrisal etc. Begin with the route between Dhaka and Chittagong.
If there are car factories they should be export oriented. Private cars ownership should be discouraged. Public transport and bicycle is optimal for BD.
If BD goverment allows car factories then there would be a immense pressure to allow cars to be sold locally.
No need and BD has plenty of other industries to provide the needed skilled jobs.