Three 2018-2019 model minivans were recently put through the paces of the passenger-side small overlap test conducted by the Insurance Institute for Highway Safety (IIHS), earning a range of ratings that cover the spectrum.

Specifically, the Honda Odyssey captured a good rating, the Chrysler Pacifica earned an acceptable rating and the Toyota Sienna was given just a marginal rating by the agency.

A small overlap crash occurs when just the front corner of the vehicle strikes another vehicle or an object such as a tree or utility pole. IIHS began rating vehicles for occupant protection in a driver-side small overlap front crash in 2012 and added the passenger-side test last year to make sure occupants on both sides of the vehicle get equal protection.

Because a good or acceptable rating in the passenger-side test is one of the requirements to earn a 2018 Top Safety Pick+ award, manufacturers have been making improvements in a quest to secure the award.

For example, IIHS notes that in these latest passenger-side tests their engineers did not find any performance issues with safety belts or airbags, as they have uncovered in the past. However, structural issues on the right side of the vehicles remain a concern.

For example, the Sienna's structure rated poor in the passenger-side test. It allowed as much as 20 inches of intrusion in the lower occupant compartment and more than 16 inches of intrusion at the dashboard.

The Pacifica did not fare much better in terms of structure. Marginal ratings for structure kept the Pacifica from achieving the top rating in the passenger-side small overlap test. Measures from dummy sensors indicated low risk of injury, helping to offset the less-than-stellar structural rating.

IIHS points out that the Pacifica's passenger-side rating is based on two crash tests — one by IIHS and the other by Fiat Chrysler as part of the IIHS frontal crash test verification program.

The Pacifica and Odyssey are IIHS 2018 Top Safety Picks. Both were among the qualifiers when IIHS announced initial winners of the 2018 awards in December 2017. Each vehicle earned a superior rating for front crash prevention and have acceptable-rated headlights. Better headlights would have secured Top Safety Pick+ awards for these two minivans.