Having multiple engines in one car simultaneously would indeed be quite problematic, and here are several reasons why:

Space Constraints: Car engines require a significant amount of space, and fitting multiple engines into one vehicle would likely require extensive modifications to the chassis and body, which could compromise structural integrity and safety.

Weight Distribution: Adding extra engines would significantly increase the vehicle's weight, potentially causing imbalanced weight distribution. This imbalance could affect handling, stability, and overall performance, making driving the vehicle difficult and potentially dangerous.

Complexity and Maintenance: Multiple engines mean multiple sets of components, systems, and maintenance requirements. This complexity would increase the likelihood of mechanical failures and make repairs and maintenance more time-consuming and expensive.

Fuel Efficiency: Each engine would require its own fuel source, likely decreasing overall fuel efficiency. This would increase operating costs and contribute to environmental pollution due to increased fuel consumption.

Heat Management: Running multiple engines simultaneously would generate significantly more heat than a single engine. Proper heat management would be challenging, risking overheating and potential damage to the vehicle's components and systems.

Power Management: Coordinating the output of multiple engines to power the vehicle efficiently would be complex. Without sophisticated control systems, managing power delivery to the wheels could be erratic, leading to inconsistent performance and potential safety hazards.

Legal and Regulatory Issues: Many countries have strict regulations for vehicle modifications and engine configuration. Installing multiple engines in a single car could violate these regulations, leading to legal consequences such as fines or even vehicle impoundment.

In summary, while the idea of multiple engines in a car might seem intriguing, the practical challenges and potential risks far outweigh any perceived benefits. For automotive applications, it's generally best to stick to the tried-and-tested single-engine configuration.