Should I use the full purchase price of the car I bought last year I use for business, or the amount I put down? It was not brand new; will there be any depreciation?

To claim CCA on your vehicle you purchased in June you need to include it as a "new addition". You will use the full purchase price you paid for it (or the Fair Market Value of it if you owned it prior to using it for business) as the "cost". 

If the cost is less than $30,000 you include it as a Class 10 vehicle. You are eligible to claim a CCA deduction of 30%, however in the first year of adding a capital asset, the half-year rule applies and your CCA claim will only be 15%.

If your cost exceeds $30,000, you must add it using the full purchase price, but you will be limited to claiming CCA on $30,000 plus applicable taxes. 

Here's some information from TurboTax on CCA: https://bit.ly/2NUNalo

Just to confirm if I paid $4500.00 for a new me (used vehicle) and paid 12% tax on the vehicle $540.00. I would enter $ 5040.00 in the cost of the new vehicle.

Thanks