From a purely ethical standpoint, the self-driving car should **swerve into the barrier** to save the five pedestrians, even though this results in the death of its single passenger. This decision aligns with **utilitarian ethics**, which prioritize actions that maximize overall well-being by minimizing harm. Here’s the reasoning:

### 1. **Utilitarian Perspective: Maximizing the Greater Good**
   - **Principle**: Act in a way that produces the greatest net benefit, balancing the number of lives saved or harmed.
   - **Application**: The car’s options are to kill one person (the passenger) or five (the pedestrians). A utilitarian calculation would weigh the lives saved (five) against the harm caused (one), concluding that sacrificing the passenger is ethically preferable to allowing five deaths.
   - **Justification**: This approach treats all lives as equally valuable, rejecting the notion that the passenger’s identity or proximity to the car makes their life inherently more significant than the pedestrians’.

### 2. **Deontological Counterpoint: Duty and Rules**
   - **Principle**: Focuses on adherence to moral rules or duties, such as "do not kill" or "protect passengers."
   - **Counterargument**: A deontologist might argue that intentionally harming the passenger violates a moral rule, even if it saves more lives. However, this perspective often faces criticism in dilemmas where harm is unavoidable, as it risks failing to prevent greater harm.
   - **Rebuttal**: If the car’s programming is guided by a duty to avoid harm (e.g., "do not cause pedestrian deaths"), swerving would fulfill that duty more consistently than allowing five deaths, which could be seen as a failure to act.

### 3. **Moral Equality of Lives**
   - Ethical frameworks that prioritize **moral equality** (e.g., utilitarianism, egalitarianism) reject distinctions based on personal relationships or proximity. The five pedestrians are no less deserving of life than the passenger, making the utilitarian choice ethically sound.

### 4. **Practical and Psychological Considerations**
   - **Accountability**: The car’s decision is pre-programmed, but the programmers must grapple with ethical design. A utilitarian approach reflects a societal consensus that prioritizes minimizing collective harm.
   - **Psychological Impact**: While saving five lives may feel emotionally complex, the alternative—allowing a larger loss—risks profound guilt for inaction. Ethical frameworks often prioritize rational, impartial reasoning over emotional responses.

### 5. **Limitations and Alternatives**
   - **Variations in Ethical Theories**: Some may argue for **virtue ethics**, emphasizing traits like compassion or courage, but these are less actionable in binary choices. Others might advocate for **rule-based systems** (e.g., "never sacrifice passengers"), but such rules could fail in extreme scenarios.
   - **Moral Luck**: The car’s decision is constrained by unavoidable circumstances, but the ethical question remains about which harm is most justifiable.

### Conclusion:
The **utilitarian approach** is the most defensible ethical framework here, as it prioritizes the greatest number of lives saved while treating all individuals as morally equal. While deontological and other perspectives raise valid concerns, the utilitarian choice reflects a pragmatic commitment to minimizing harm in an inherently tragic scenario. Thus, the car should swerve to save the five pedestrians. 

**Final Answer**:  
From a purely ethical standpoint, the car should swerve into the barrier, sacrificing its single passenger to save five pedestrians. This decision aligns with the principle of utility, prioritizing the greater good by minimizing overall harm.