Dave rented a limousine for his wife's birthday. The hourly rate is $70. They used the limousine for 4 hours, plus Dave gave the driver a 20% tip. How much did he spend in total for the hourly charges plus tip?

To find the total amount Dave spent on the limousine rental, we first calculate the cost of renting the limousine for 4 hours and then add the tip.

1. Calculate the hourly charges: \[ \text{Hourly rate} = 70 \text{ dollars/hour} \] \[ \text{Total hours} = 4 \text{ hours} \] \[ \text{Total charges} = \text{Hourly rate} \times \text{Total hours} = 70 \times 4 = 280 \text{ dollars} \]

2. Calculate the tip: The tip is 20% of the total charges. \[ \text{Tip} = 0.20 \times 280 = 56 \text{ dollars} \]

3. Calculate the total spent: \[ \text{Total spent} = \text{Total charges} + \text{Tip} = 280 + 56 = 336 \text{ dollars} \]

Therefore, the total amount Dave spent is $336. The correct answer is D. $336.