Car rental protection offered by rental companies can cost $15 to $30 a day—in 10 days, that could be as much as whopping $300. Alternatively, a credit card with rental insurance will offer the same coverage at no extra cost—and even if it does, it's significantly cheaper than what rental companies offer. 

For example, The Platinum Card® from American Express charges a flat fee of $19.95 or $24.95 per rental period (not per day) for primary coverage.