You would treat this as if you actually purchased the vehicle in the year. Your cost of this addition will be the amount you actually paid for the buy-out (or residual value), and you will use the date you made the buyout as your "date of acquisition". The half-year rule will apply as you have actually purchased this vehicle from leaseholder.

And yes, you would add this vehicle as a Class 10 asset. 

https://turbotax.intuit.ca/tips/what-is-capital-cost-allowance-2016

What happens if a few months after your buy-out you have an accident with total loss of the vehicle and the insurance company paid not the buy-out price but the fair market value of the car (which is higher)?

Is that considered a capital gain and therefore treated as income? Or is it considered that during the lease payments period you've paid part of the vehicle which you finished paying with the buyout?

What I mean is the car has been paid with a lease payments (with the right to own it) plus the final buyout amount, the accident caused a total loss of property and the fair market value amount received was less than the original manufacturer's price used in the lease calculations.  Is there any capital gain in this case?