Mayor Walter E. Washington proposed a wide-ranging 1978 legislative agenda yesterday, including requests for Congress to grant the city greater budget autonomy, the authority to select its own judges, full voting representation in congress and the power to impose a commuter tax.

The mayor's package of nearly 100 legislative proposals also include measures that would help low-income city residents purchase homes, strengthen controls over sex-oriented entertainment in nightclubs, impose regulations on group health firms in the city and make it harder to repossess the automobiles of owners whose car payments are arrears.

Many of the proposals were not new or original and most were not detailed, since the legislative package is merely an outline of the law-making offensive the mayor intends to pursue throughout the year. Some -- such as the commuter tax --are perennial wishes that the city has always been denied in the past.

The proposals appeared to be the latest move in what many believe to be a well orchestrated plan to paint the mayor as far more responsive than his political rivals have usually protrayed him and to do so at a time that Washington is seriously considering seeking re-election.

"This is a far-reaching program designed to strengthen home-rule authority, expand services to the community and improve effectiveness of government operations," the mayor said, through a spokesman.

The package even contains one request that would strengthen the mayor's own office in its duels with the City Council: It asks a change in the Home Rule charter that would require at least 10 City Council votes to override a mayoral veto. At present, only two-thirds of the council members present at any meeting -- anywhere from five to nine on the 13-member panel -- can override mayoral vetoes.

Some of the proposals likely to affect the most city residents are in usually overlooked areas such as consumer protection. licensing and inspections, zoning and human resources.

The mayor would like to revise the consumer credit procedures used in automobile financing to prohibit repossesion of automobiles without notice to the debtor and provide a 30-day grace period between the time default occurs and repossession takes place.

Also proposed was registration of all stores that offer their own credit plans, city standards for layaway plans and requirements that all firms servicing as rental referral agencies be licensed by the city as real estate brokers and keep more up-to-date lists of available housing.

To meet a growing concern among some city residents over an increase in sex-oriented live entertainment, the mayor is proposing a change in the city Alocholic Beverage Control Act that would give the ABC agency more leverage "to contain and control the growth of pornography and obscenity."

The mayor's housing assistance plan, which carried no long-rang price tag in yesterday's proposal, is modeled on the Home Purchase Assistance Program formerly financed through the old Model Cities Program. As outlined in yesterday's proposals, the new plan would provide down payment assistance in the form of a deferred payment loan. One million dollars for such a program -- enough to assist 110 request. families -- is in the city's 1979 budget $3.8 million to provide financial assistance to medical and dental students who agree upon graduation to serve in areas of the city that now lack adequate professional medical services.

About 200 students could be subsidized annually with the $3.8 million.

The mayor is also asking several changes in laws affecting other social services, including authorization for city health clinics to offer premartial tests, emergency dental treatment for children and alcholic treatment services not currently available.

The city would gain $1 million to $2 million under a proposal by Washington to regulate and tax group health organizations, which are now tax exempt.

Several changes are recommended in city laws affecting motor vehicle registration. Among them are a change in the definition of commercial vehicles that would allow vans and recreational vehicles to be parked on the street. Many such vehicles are now classified as commercial and cannot legally park on some residential streets or receive residential parking permits.

Among the changes in criminal law being asked is one that would prohibit the admission as evidence in a rape trial of information on the previous sexual conduct of the alleged victim. The proposal would also allow guilt in such cases to be proven without corroborating testimony and without necessary evidence of physical injury.

Most of the proposals on city fiscal affairs and expanded home rule paralleled a report issued last fall by a special White House Task Force on District of Columbia problems.

They included multiyear authorizations for the federal payment, which is the U.S. government's annual reimbursement to the city for the loss of taxes from federally occupied land.

The mayor also asked for $37.8 million from Congress for the city's 1979 share of Metro rail construction costs.