Step 1: Start out by drawing a rectangle with an oval placed inside of it as shown.
Step 2: Outline the frame over the shapes created in step 1.
Step 3: Add two circles, this will be the wheels.
Step 4: Complete the bottom frame of the car.
Step 5: Sketch the top portion of the windshield, seats, side door and antenna.
Step 6: Fill in rims of the tires, and add more details to the headlights, and front fender below the grill.
Step 7: The next thing to do now is to draw out the beginning lining to form the car door, door handle, and then some of the back bumper. When that is done, start sketching out the back seats, and add detailing to the folded roof.
Step 8: Choose the best color you like and shade in the convertible. I hope you liked learning how to draw a convertible.