There are multiple schools of thought - some people may want to keep the car for the longest time possible, some might want to replace it every few years, and some might want to replace it every year. Hence, there is no right or wrong time to sell your vehicle.
If there is a car you're lusting after, or if minor niggling issues keep cropping up with your Renault Triber, then it certainly makes sense to replace it immediately. However, if the car is serving you well without any issues, you may hold on to it for a few more years. Interestingly, the resale value of a vehicle falls the steepest in the first two years, after which its residual value will reduce gradually. So the difference in resale value at the end of five years and seven/eight years won't be drastic if the car is looked after well. We'd advise you to sell it if you are ready to upgrade to maybe a Maruti Suzuki Ertiga/XL6 or Kia Carens Clavis. 
