The Saturn Ion is a good example of that. When it appeared in 2003, the Ion represented a major improvement over the old Saturn S-series. Yet our impressions of it were negative. We found the seats uncomfortable and its levels of refinement were average at best. However, Saturn has continued to update and refine the Ion over the past three model years, and we came away with positive impressions of the current models. Most of the things we complained about have been changed and refinement has been improved overall.

The most substantial changes came for 2005: Larger and more supportive seats have replaced the barstools used previously, and a larger steering wheel provides a more comfortable grip. Suspension tweaks have resulted in a smoother and quieter car that's more pleasant in everyday use. At the same time, the handling is sharper, making it more fun to drive. A new four-speed automatic built by GM replaces outsourced transmissions that proved problematic. And the appearance of the sedan was greatly improved with a new grille.