If you wish to test that observed trends are within model distribution, you would use the standard deviation of the trends of models and you would have the wide confidence intervals you expected. (julesandjames.blogspot.ru)
Four - wheel, four - wheel disc anti-lock disc brakes with electronic brake force distribution and traction control system on all models (media.fcanorthamerica.com)
In the preceding model the distribution was a neutral 50:50. (motor1.com)