ITR for 44AE

If you opt for presumptive taxation then you have to maintain such taxation for 5 years

Business profit will remain as it is under PGBP. 44Ae you can continue. if you discontinue then for next 5 years you won't be allowed to opt for 44AE.

5 years restriction is in section 44AD and not in 4AE.

An assessee may claim lower profits and gains than the profits and gains specified in sub-sections [1] and [2], if he keeps and maintains such books of account and other documents as required under sub-section [2] of section 44AA and gets his accounts AUDITED and furnishes a report of such audit as required under section 44AB.

Where is shown sale of vehicle ? 

If filled under 44AE