Final answer:
The best practice when driving up or down hills is to shift to a lower gear for better control and power. Cruise control is not recommended in hilly areas as it may not handle speed adjustments when needed.
Step-by-step explanation:
When driving slowly up or down hills, a good practice is to shift to a lower gear. This not only provides more power at lower speeds but also offers better control of the vehicle. Additionally, using lower gears can help in engine braking when going downhill, reducing the reliance on brakes and preventing them from overheating. While cruise control is useful on long and steady drives, it is not advisable in hilly terrain where speed adjustments are frequently needed.