It is difficult to provide a definitive answer to the question of which programming language is used in the ECU of a car, as different car manufacturers and ECU developers may use different languages depending on their specific needs and preferences. However, some commonly used programming languages in the development of ECUs include higher-level languages like Python or Java, which are sometimes used for the development of diagnostic software or simulation tools, as well as more low-level languages like C and C++, which are often used for their efficiency and control. Assembly language may also be employed in certain tasks requiring direct hardware access. Ultimately, the choice of programming language in ECU coding is akin to an artist choosing their paint, with each language having its unique properties and suitability for different tasks.