Patowato Motors Limited leases second-hand German sports cars for special occasions. It started business on 1 January 20X6 and has decided to depreciate the cars on a straight line basis at 25% per annum on cost at the year-end. During the years 20X6 to 20X9 the following purchases and sales of cars took place.

20X6 Acquired 20 Porsche 928 Turbos at a cost of GH₵18.6 million each
20X7 Purchased 6 Porsche vehicles for a total cost of GH₵108.6 million.
20X8 Traded-in two of the cars acquired in 20X6 and received an allowance of GH₵9 million each which was set against the purchase of a further two cars costing GH₵19.8 million each
20X9 Replaced 15 cars purchased in 20X6 with another 15, each of which cost GH₵21 million. A trade-in allowance totalling GH₵48 million was received

Patowato Motors Limited prepares accounts to 31 December each year.
The finance director of Patowato Motors Limited, who is a qualified accountant, intends to apply the revaluation model to those of the company’s sports cars that appreciate in value. He intends to recognise revaluation increases in profit or loss and has told colleagues that this will boost the directors’ bonuses.

Required
(a) Prepare a vehicle account, an accumulated depreciation account, a depreciation account and a disposals account for the years 20X6 to 20X9.
(b) Explain why the finance director’s suggestion to revalue some vehicles is unethical