This bubble chart shows the relationship between horsepower and engine size, where each car is represented by a circle whose radius encodes car age and whose color corresponds to the car model. The tooltip reveals the model name on hover. The visualization uses d3.v7 with SVG rendering, including axis scales, a sqrt scale for bubble size, a color scale ordinal with the Tableau10 scheme, and mouse event handlers for the tooltip. Data is loaded from a CSV file using `d3.csv`.