PS: If you want to find out MG's own estimate rate of depreciation on this car, then ask them for an Operating Lease quote: IE: -price of car on road. -full servicing for 4 years/80,000 kms -guaranteed buy back price after 4 Yrs/80,000 kms.
And there you have it.
For a second/comparative quote you can always ask an independent finance co for ditto. This can constitute the basis for your cost of ownership over 4 years Of course you'll have to factor-in insurance, rego, charging costs, tyres etc that are not included in the Operating Lease package.
But the bottom line is that you'll have the rate of depreciation by those with skin in it.