First, Tesla appears unhappy that CR expects the new-to-market Tesla Model 3 to be of average reliability, which is generally a positive projection for any first model year of a car. This expectation is based on CR’s 2017 Annual Reliability Survey, measuring the dependability as opposed to the satisfaction, of more than 300 car models, model year 2000 to 2017, using the responses of individual owners of more than 640,000 vehicles. We provide this information to help people make informed purchasing decisions as new products reach the market.…how they measure it…CR conducts a battery of 50 standardized tests across all the vehicles we review – we have a lot of mileage in this arena. We also continuously update our ratings as new surveys are conducted and we test the cars we purchase to reflect the current realities of what a consumer should expect in the marketplace. (That’s right, purchase. CR does not accept any advertising and purchases the products we rate like any other regular person.) The Model S rating has changed over time, going up and down, as new data becomes available.