AMERICAN MOTORS, GM AND CHRYSLER SUE FTC ... to halt wide-ranging probe of the automotive industry. The manufacturers are asking the courts to put a stop to a two-year wide-ranging investigation that has "unprecedented vagueness and unlimited scope," according to the suit. The FTC hasn't said what purpose the investigation will serve and the latest court action was prompted by wide-ranging subpoenas recently issued for data and documents dating as far back as 1946. GM indicated that it has spent as much as $700,000 just to estimate the burden imposed by the subpoenas and added that it would cost about $110-million to track down and produce the requested information.

GM CUTS PRICE OF SPORTY COMPACTS FOR 1979 ... by equipping the cars with a package of options as standard equipment without raising the price of the vehicles. The move is seen as an effort to make the vehicles more competitive with Ford and Lincoln-Mercury's restyled Mustang and Capri. The package, which will in effect reduce the price from $29 to $157 over comparably equipped 1978 models, will be added to the Monza, Sunbird, Skyhawk and Starfire models. The equipment includes AM radio, body side moldings, tinted glass, sport steering wheel and sport mirrors.

CHRYSLER'S NEW OMNI/HORIZON TWO-DOOR HATCHBACKS MAY NOT BE AVAILABLE UNTIL JANUARY 1 ... according to sources reporting to Automotive News. The cars, which are scheduled to go into production late this month, are called the Omni 024 and Horizon TC3 and are completely different from the four-door models. The official launching of the models will come during December.

INDUSTRY LEADERS PREDICT ANOTHER YEAR OF HIGH TOTAL SALES ... as the model year begins. GM Chairman Thomas Murphy predicts 11.5-million passenger cars will be sold during the 1979 model run along with more than four million trucks for an all time high of 15.5-million vehicles. Murphy predicted last year that the 1978 total would be 15.5-million and almost hit the mark as final figures for '78 are predicted to be about 15.4-million units. Ford's William O.Bourke, executive vice president of the company's North American operations, predicts total sales will reach about 15.3-million units. He feels 11.2-million cars will be delivered, while trucks will account for 4.1- million units, an all-time high for the utility vehicles.

NHTSA ADOPTS STANDARDIZED VEHICLE IDENTIFICATION NUMBER SYSTEM ... proposed earlier this year. The new system is a 17-character numeral and will become effective January 1, 1980 on all passenger cars and September 1, 1980 on most other vehicles. The new format features three sections, the first of which contains three characters identifying the manufacturer, make and vehicle type. The second section (five characters) will identify the vehicle's line, series, body, type, engine type, gross vehicle weight rating and restrain system type. The third section, with eight characters, will list vehicle model year, manufacturing plant, and the production sequence number of the vehicle. A check digit, located after the second section will also appear on any transfer documents.

SHORT TAKES ... Chrysler Corporation has announced that it is planning to make available a limited number of air bags on its intermediate Diplomat and LeBaron series in 1981. Federal law does not require the passive restraint in that size of vehicle until 1983, but the company indicated that it wanted to gather some field experience before installing the devices on all its car lines ... Chevrolet is getting on the diesel bandwagon by working on a V6 diesel powerplant for use in its compact and mid-size cars. A V8 diesel is expected from the division in 1981-82 and a four-cylinder diesel powerplant may be in production as early as 1982 ... Associates Leasing has moved from South Bend, Indiana, to suburban Chicago.