Crude Oil Price Volatility & Refining Margins: Fluctuations in the price of crude oil and the crack spread (difference between crude and refined product prices) directly impact MPC's profitability, as these factors determine refining margins.

Regulatory & Environmental Compliance Costs: Increasingly stringent environmental regulations, including emissions standards, carbon pricing, and fuel specifications, can lead to significant capital expenditures, operational costs, and potential liabilities for MPC's refining and marketing operations.

Decreasing Demand for Refined Products: Long-term shifts in consumer behavior towards electric vehicles, improved fuel efficiency, and renewable energy sources could reduce demand for gasoline, diesel, and jet fuel, impacting MPC's future revenue streams and asset utilization.