If you are considering towing with your vehicle, you should first check with your country's Department of Motor Vehicles to determine their legal requirements.
Since laws vary the requirements for towing trailers, cars, or other types of vehicles or apparatus may differ. We recommend that you ask an authorized Kia dealer.
WARNING - Towing a trailer
If you don't use the correct equipment and/or drive improperly, you can lose control when you pull a trailer. For example, if the trailer is too heavy, the brakes may not work well - or even at all. You and your passengers could be seriously or fatally injured. Pull a trailer only if you have followed all the steps in this section.
WARNING - Weight limits
Before towing, make sure the total trailer weight, GCW (gross combination weight), GVW (gross vehicle weight), GAW (gross axle weight ) and trailer tongue load are all within the limits.
✽ NOTICE - For Europe
CAUTION
Pulling a trailer improperly can damage your vehicle and result in costly repairs not covered by your warranty. To pull a trailer correctly, follow the advice in this section.
Your vehicle can tow a trailer. To identify what the vehicle trailering capacity is for your vehicle, you should read the information in “Weight of the trailer” that appears later in this section.
Remember that trailering is different than just driving your vehicle by itself. Trailering means changes in handling, durability, and fuel economy. Successful, safe trailering requires correct equipment, and it has to be used properly.
This section contains many time-tested, important trailering tips and safety rules. Many of these are important for your safety and that of your passengers. Please read this section carefully before you pull a trailer.
Load-pulling components such as the engine, transaxle, wheel assemblies, and tires are forced to work harder against the load of the added weight. The engine is required to operate at relatively higher speeds and under greater loads. This additional burden generates extra heat. The trailer also considerably adds wind resistance, increasing the pulling requirements.
Kia Niro 2017 (DE HEV) Service Manual: Coolant Repair procedures
Refilling And Bleeding
Never remove the cap when the engine is hot. Serious scalding could be
caused by hot fluid under high pressure escaping from the reservoir.
  ...
Kia Niro 2017 (DE HEV) Service Manual: Front Seat Belt Retractor Components and components location
Component Location
1. Front seat belt retractor
...