More of a tax question but involes using the margin loan feature.

So I'm trying to buy a car for about 30k and have about 250k in investments.

The following is the plan:

1. sell investments that have gains and and investments that have losses so that the losses cancel out the gains hence no capital gains tax.
2. withdraw the the cash from investments sold
3. use margin to buy safe stocks (td, bns, enb). The example stocks have a looooong history of paying and increasing dividends and have a dividend yield of greater than the 5% margin interest.
4. I believe interest paid on margin is tax deductible so the real interest would end up being 5*(1-t) assuming a 35% tax rate that brings the interest rate down to 3.25%

Essentially, I buy the car and amount invested doesn't change. I guess the biggest risk is a sudden drop in stock price causing a margin call.

Soo tell me

1. why this wouldn't work
2. why it's a bad idea