Hi Phil. Depreciation is nil, as the car is so old. In fact, because it is a fairly rare Classic LSE, it might even appreciate in value.
Maintenance costs come down to only what I cannot do myself; in the ten months since I bought this particular car (its my fifth Classic RR), it has cost just over £400, but these are "capital" repairs, which hopefully will not recurr, brake pipes for MOT, and two height sensors for the air suspension. Anything which doesn't involve lying underneath, I do myself.
Even allowing for heavy fuel costs, it is cheap, luxury, reliable motoring.
If I had to run it on petrol, however, that would be a different tale...........!