California → Arizona · Interstate 5 (San Diego Freeway)
The drive from San Diego, California, to Tucson, Arizona, covers about 688 km (428 miles) along Interstate 5 (San Diego Freeway), with an estimated travel time of 6h 33m in normal traffic conditions. San Diego is the southern California port city on the Mexican border, while Tucson stands out as the second-largest city in Arizona and gateway to the Sonoran Desert. Sales reps, consultants, real-estate agents and field service professionals who run this route regularly typically depart at sunrise to clear the urban congestion before rush hour and arrive in time for scheduled morning meetings. It also pays to scout two or three reliable fuel-and-rest stops along the way before departure. Assuming average fuel economy of about 26 mpg on regular unleaded, the trip burns roughly 62.5 liters (16.5 gallons), costing about $57.50 at typical pump prices. For mileage reimbursement, applying the IRS standard mileage rate (2025) of $0.43/km ($0.69/mile) yields a one-way payout of $295.84. Keep the trip log, business purpose, odometer readings, and exact route documented in your Clara receipt for IRS compliance and internal audit defensibility.