Tuk-tuks are still the default. The classic Cambodian tuk-tuk is a motorbike with a covered passenger trailer; the newer Indian-style auto-rickshaw (called "rickshaw" or "Bajaj") is faster and air-conditioned. Use the PassApp or Grab app to call either — both show metered fares, save you from haggling, and dispatch within minutes. Trips across the centre rarely cost more than US$2–3.
Motorbike taxis (moto-dop) are everywhere and the cheapest option, but require some local knowledge and confidence in traffic.
Walking works only in short bursts — pavements are often blocked, and the heat is brutal much of the year. The riverfront promenade and the BKK1 grid are exceptions and pleasant on foot.
Renting a motorbike or scooter is possible but not recommended for first-time visitors. Phnom Penh traffic is chaotic, road manners are poor, and a serious accident a long way from home is the most common way for tourists to end their trip. If you must, helmets are legally required and rarely enforced.
There is no metro. A few BRT bus routes run on the main boulevards but are slow and rarely used by visitors.