Patient physiology and crash characteristics are essential components of field triage for motor vehicle crashes. We aimed to identify prehospital information that predicted high injury severity or critical patient condition on hospital arrival. The association of demographics, shock index (SI), Glasgow Coma Scale, and 10 crash characteristics of trauma activations for motor vehicle crashes with injury severity score (ISS) ≥ 16 and a composite of hypotension, need for blood transfusions, or immediate operation was determined using univariate and multivariate analyses. A total of 133 of 498 patients (27%) had ISS ≥ 16; SI ≥ 0.9, Glasgow Coma Scale ≤ 8, speed ≥ 55 mph, seatbelt use, airbag deployment, ambulatory patient, severe vehicle damage, ejection, and extrication were associated with ISS ≥ 16. Only abnormal SI and high speed remained independent predictors for ISS ≥ 16 with Odds Ratio (OR) = 10.76 (95% confidence interval (CI), 1.14-101, P = 0.04) and OR = 10.37 (95% CI, 1.48-72.93, P = 0.02), respectively. SI ≥ 0.9 predicted the composite outcome with OR = 5.92 (95% CI, 2.32-15.08, P < 0.01). Many commonly reported crash characteristics did not predict clinically important outcomes. Improvements in road and vehicle safety may be resulting in lower injury severity despite major crash mechanisms.