There are a lot of factors to consider when determining whether or not a car is reliable. For the fourth generation Rams, reliability is largely dependent on model year and engine type. Generally speaking, the newer the model year, the more reliable the vehicle will be. Additionally, Rams with V6 engines tend to be more reliable than those with V8 engines.
That said, there have been some issues reported with fourth generation Rams. Common problems include transmission failure, engine knocking noise and excessive oil consumption. However, these problems are typically only seen in older models or those with high mileage. Overall, fourth generation Rams are generally considered to be reliable vehicles.