Based on your query, I recommend using DreamStudio. This tool uses AI to generate images based on text prompts, which aligns perfectly with your need to create a diagram of a car parked on a hill.
You can simply input your text description into DreamStudio and adjust the style and other elements of the image as needed. Once you're satisfied with the generated image, you can download it for use in your lesson. This feature can be a great way to visually represent concepts, making them easier for your students to understand.
Remember, DreamStudio operates on a credit system, so you'll need to purchase credits to generate images. However, new users do receive 25 free credits to start with.