Not going to happen unless it's legislated. You can't trust the calculation given by the cars, and the automakers absolutely do not want every car to track this since they leave themselves open to lawsuits when the numbers don't meet whatever was advertised. For example, the readout on my car gives L/100km but it's rounded to the whole number! So it's useless even if it was accurate because the precision is gone.
The real issue here is that those numbers depend entirely on how the end user drives the car anyway. I used to own a Subaru Legacy GT LTD, with a turbo. The stock 0-60 time was 4.9 seconds. It could take off in a hurry. When I felt like being a bit on the sporty side, I would often get an abysmal 14-15MPG. If I were feeling a bit more conservative, I could easily get 24MPG in the same conditions. If I drove especially fast on the highway, I would get 21MPG. If I drove conservatively, I could get 28MPG. So you can't just use real world numbers because those can be fudged just as easily.