The Kia Rio, now in its fourth incarnation, is the Korean automaker's best-seller with sales close to 475,000 a year. While it is overshadowed in the UK by the European-built Sportage crossover and Ceed range, it accounts for almost one-sixth of the company's sales. Continuing just-auto/QUBE's review of interior design and technology trends, we take a closer look inside to see how it compares to its predecessor.