Cadillac CT5’s Shocking IIHS Failure: Driver’s Head Hit Sill

The 2026 Cadillac CT5 just did something you rarely see from a modern luxury sedan: it earned Poor ratings in two key Insurance Institute for Highway Safety (IIHS) crash tests, including the group’s tougher side impact evaluation. That sits awkwardly beside the CT5’s 5-star overall safety scores from the National Highway Traffic Safety Administration (NHTSA) and raises fresh questions about what those stars really capture.

For anyone weighing a CT5 as a daily driver, company car, or fleet sedan, the issue isn’t simply that it “flunked” a test. The real story is how the driver dummy’s head and chest behaved in IIHS’ newer SUV-style crash scenarios and why rivals like the BMW 5 Series and even the Toyota Corolla fared better when the same forces were applied.

Where The 2026 Cadillac CT5 Fails IIHS Tests

The main trouble spot for the 2026 Cadillac CT5 is IIHS’ updated side impact test, which uses a roughly 4,200-pound moving barrier shaped like a modern SUV hitting the driver’s side at about 37 miles per hour. In that hit, the CT5’s driver dummy slid down past the side curtain airbag and struck the window sill and door trim panel, with a peak head load of 161 g and a HIC-15 of 1,282—values linked to a high risk of severe head injury.

IIHS also ran the refreshed CT5 through its updated moderate overlap front test, again with weak results. Premium Luxury trims between 3,663 and 3,802 pounds showed a moderate risk of chest injury and a likely head or neck injury for the rear seat dummy, which pulled the overall rating down to Poor even though the front structure itself held up well.

There are some bright spots. In the same side crash, the rear passenger dummy earned a Good rating for injury measures, showing the back-seat side structure and airbags worked in that scenario. But IIHS also recorded Poor ratings for the CT5’s base headlights and its vehicle-to-vehicle front crash prevention system, so it misses the group’s Top Safety Pick awards entirely and undercuts Cadillac’s broader push to keep traditional sedans relevant.

IHS vs NHTSA Scores

So how can a car with 5-star NHTSA ratings look this bad in IIHS testing? NHTSA’s New Car Assessment Program focuses on a smaller set of standardized frontal, side, and rollover tests and turns them into a single star score, while IIHS layers on newer, tougher scenarios with separate grades from Good down to Poor. That lets a sedan like the CT5 ace federal tests yet struggle with SUV-style side impacts or rear-seat protection in more demanding evaluations.

Cadillac has leaned hard on the government scores, with a spokesperson stressing confidence in the CT5’s safety and its 5-star NHTSA rating. On that metric alone the car looks strong, and earlier model years hit the same top-line result. But IIHS’ Poor crash ratings, plus weak marks for automatic emergency braking and headlights, show the CT5 trails the best midsize sedans in detailed crash protection and crash avoidance, especially against newer platforms engineered around the latest IIHS protocols from day one.