Any board of education having power to provide for the transportation of school pupils in its district to and from school may provide such transportation by a bus or buses owned by it or may enter into contract for such transportation, approved by the county superintendent, for a term not exceeding 4 years.
All multiyear contracts made pursuant to the above taking effect subsequent to September 1, 1975 may, at the discretion of the local board of education, and subject to approval by the county superintendent, be increased not to exceed 7 1/2 annually of the original yearly contract cost beginning with the second year of the contract.