Car rental prices aren't fixed — they move with demand, and demand moves with holidays, school breaks, and local events. Booking in the same city can cost twice as much during a busy week as it does a month later.
Generally, midweek pickups (Tuesday–Thursday) run cheaper than weekend pickups, since leisure travelers cluster around weekends. If your dates are flexible, shifting a pickup by even a day or two can meaningfully change the price.
Shoulder seasons — spring and early fall — tend to offer the best combination of good weather and lower demand in most US destinations. Summer and major holidays are consistently the most expensive stretches of the year.
Booking early helps too. Rates tend to rise as a date approaches and inventory tightens, particularly for popular vehicle classes like SUVs and convertibles.