WASHINGTON — General Motors Corp.'s Chevrolet Astro minivan had the lowest driver death rate in the U.S. from 2002 through 2005, and a version of GM's Blazer sport utility vehicle had the highest, according to a vehicle crash study.

The safest models still in production were all midsize and larger imports, the Insurance Institute for Highway Safety said after examining federal accident records of vehicles from the 2001 through 2004 model years.

The study found small cars continue to have the highest death rates, while SUVs are getting safer. Eleven of the 16 vehicles with the highest death rates are mini or small models, while half of the safest models are SUVs.

The Astro had seven deaths per million registered vehicles in the period, while the two-door, two-wheel-drive model Blazer had 232 deaths per million, the report said. Both vehicles were last produced in 2005.

GM said it's hard to draw conclusions from the report without knowing what driver behavior was involved.

"We know from decades of work that whether a driver dies in a crash has more to do with behavior than with the vehicle," GM spokesman Alan Adler said.

The average driver death rate has fallen to 79 per million registered vehicles from 110 per million from 1990 through 1994, the Arlington, Va.-based institute said.

"This is a big improvement over time," Anne McCart, the institute's senior vice president for research said in the report.

SUVs are getting safer thanks to the use of anti-rollover technology such as electronic-stability control, institute spokesman Russ Rader said.