WASHINGTON — Consumers who buy minicars to economize on fuel are making a big tradeoff when it comes to safety in collisions, according to an insurance group that slammed three minimodels into midsize ones in tests. In a report prepared for release on Tuesday, the Insurance Institute for Highway Safety said that crash dummies in all three models tested — the Honda Fit, the Toyota Yaris and the Smart Fortwo — fared poorly in the collisions. By contrast, the midsize models into which they crashed fared well or acceptably. Both the minicars and midsize cars were traveling 40 miles per...