General Motors said on Saturday that most of its 4,400 US dealers have agreed to upgrade their showrooms over the next four years. The upgrades include new signs, more modern interiors and lounges with free wireless internet access. In some cases, dealers might also open cafes or salons. The company announced its plans at the National Automobile Dealers Association convention in Las Vegas. GM said 3,400 dealers agreed to upgrades, and 1,000 have been completed. Article continues below GM said it also plans to give dealerships more sales and service training and encourage them to do more online marketing. If they meet all the upgraded standards, they\'ll receive quarterly payments, spokesman Tom Henderson said. Henderson said 36 per cent of GM\'s stores were built before 1970. ‘Shopping experience\' \"We\'re investing in our retail network because today\'s new-vehicle customer expects a shopping experience to match the character of the brand they\'re considering,\" said GM North America President Mark Reuss. But some dealers question the costs, which can approach $1 million (Dh3.67 million) per dealer. They say the expense would be particularly difficult for smaller dealers. The National Automobile Dealers Association released a study on Saturday recommending that auto companies better explain the need for the upgrades. It also suggests costs could be lowered if discounts were negotiated with construction companies or if dealers could use different, but comparable, materials. The association also said companies and dealers need to jointly research and determine future trends that could affect dealerships. Dealers might be able to have smaller properties with fewer cars as people increasingly shop for and order cars online, for example. The study also suggested that as car quality improves, dealers might need fewer service bays. Timothy Kool, who owns two GM dealerships in south-west Michigan, said GM is deciding whether he can keep the floor tiles he installed nine years ago. \"It\'s frustrating,\" Kool said. \"There\'s not one bit of evidence that because my tile is the same as other dealerships, my sales will improve.\"