The likelihood of injury from a car accident varies widely among different car models, but for the most part safety increases with automobile size, according to an insurance industry report.

The report on injury claims involving 207 popular models shows that small cars have by far the highest injury loss records, while station wagons and large cars often afford the greatest protection.According to the insurance group, the Mercedes-Benz SDL-SEL sedan, which is equipped with a driver-side airbag, had the best safety record with injury losses that were 58 percent lower than the average for all cars. Close behind was the Pontiac Safari station wagon.

The least safe car was the 4-door Chevrolet Spectrum, which had injury losses that were 78 percent above average, followed by the 4-door Chevrolet Sprint and 4-door Hyundai Excel, both of which had losses 67 percent above average, the report said.

Of the 10 cars with the best injury loss record, nine were categorized as "large" cars including five station wagons and vans. The Saab 9000 was the only "mid-size" car in the top 10 vehicles, ranking fifth best with injury losses 51 percent lower than average.

The 10 vehicles with the worst injury loss record were all in the small sedan or small sports car category.

Exceptions to the general trend that small cars afford the least protection include another Saab model, the Saab 900, as well as the Volkswagen Vanagon, the Toyota van, Porsche 944 coupe and Mercedes Benz 380-560 SL convertible. All are in the "small" category but had better than average injury loss records.

But except for the Saab 900, all 60 of the "small" sedan models had higher injury losses than average.

The report by the Highway Loss Data Institute, an insurance industry research group, covered 1985-87 model cars, but spokesmen said the findings can be used as a guide for later model vehicles as well.

"The loss experience of most cars is consistent from one model year to another," said Brian O'Neill, the institute's president.

The report said the results were adjusted to take into account various "non-vehicle factors" such as types and ages of drivers that might be associated with particular vehicles.

The 2-door Chevrolet Cavalier was the only mid-size car to have "substantially worse than average" injury losses - 36 percent worse than average for all vehicles.

All but two of the 35 "large" cars, station wagons, vans and speciality cars had lower than average injury losses. The 4-door Oldsmobile Delta 88 and Cadillac Fleetwood-Deville were the exceptions, ranked as average.