Usually yes, but only with the rental company's approval. Some contracts forbid crossing the border, and one traveller reported that officials didn't seem to care, but that's not something to count on. Ask in advance, and ask whether a one-way drop-off in Uganda is allowed.

You need the car's registration documents and a letter from the owner authorising the crossing. A Carnet de Passage isn't considered worth the cost for East Africa. Some overlanders do use a carnet, and it's accepted, but rental cars generally don't need one. On the Rwandan side, travellers describe handing in the temporary import permit to Rwandan customs and signing the car out before driving on to Uganda.

You'll need proof of insurance at the border. If you don't buy it locally, a COMESA Yellow Card covers Uganda, Rwanda, Kenya and Tanzania. Ask your rental company whether their policy already includes this. Some companies handle it for you, and for others you buy it separately. Check what the cover actually includes (third-party only is common) and whether it applies outside Rwanda.

A regular Rwanda visa is usually valid for 30 days per entry. The East African Tourist Visa costs less than three separate visas and lasts 90 days for Rwanda, Uganda and Kenya, but your first entry must be through the country that issued it. If you're starting in Rwanda, get it for Rwanda and enter there first. You can apply online before arrival through Rwanda's Irembo portal. Uganda's e-visa is an alternative if you'd rather arrange that side separately.

Often, yes. Rwanda asks for one at the airport and border posts. Uganda also asks for it from travellers arriving from risk areas, so carry it regardless.

Your home licence is often fine for tourists, but an International Driving Permit is cheap insurance against a stricter officer or rental company. Border officials do check licences.

Rwanda drives on the right and Uganda on the left, so you switch at the border. One overlander noted that there's no sign at the border telling you to switch. Rental cars in Rwanda are typically left-hand drive, so expect to drive from the "wrong" side in Uganda. Take the first few kilometres slowly.

For gorilla trekking in Bwindi or Lake Bunyonyi, the Cyanika crossing is the usual route. It's quiet, and travellers describe it as fast, with the Ugandan and Rwandan formalities side by side. One group reported about 45 minutes from start to finish. Gatuna/Katuna is the main Kigali–Kampala route and is busier. For both, crossings of roughly 40 minutes to over an hour are typical, though a fixer or the rental company's agent can speed things up.

Rwanda's main roads are generally smooth. Uganda's can be rough once you leave the highways. Operators recommend an SUV, since most of East Africa's road network outside the highways is in poor condition. A 4x4 is the sensible choice for Bwindi, Queen Elizabeth or Murchison Falls. Avoid driving at night, because of unlit pedestrians, livestock, boda-bodas and unmarked speed bumps.

Much of East Africa runs on cash. Carry US dollars for some fees, and local currency (Rwandan francs and Ugandan shillings) for fuel, tolls and small purchases. Card payments for visas may not work at every border post. Fill up whenever you pass a decent station, because remote areas near the parks have few.

Yes, for the headline activities. Gorilla permits (Bwindi in Uganda, Volcanoes in Rwanda), park entry and lodges in peak season (roughly June to September and December to February) are best booked well ahead. Park fees and permit prices change, so use the official Uganda Wildlife Authority or Rwanda Development Board pages for the current figures.