No credit cards. Personal checks accepted. Open weekdays 11 a.m. to 3 p.m., 6 to 10:30 p.m.; Friday and Saturday, 11 a.m. to 10:30 p.m.; Sunday, 11 a.m. to 8:30 p.m. Accessible to the handicapped.

On the underside of Arlington, just off Wilson Boulevard among the car dealerships and a cycle shop, there stands a bit of Mexico - Speedy Gonzalez' La Casita Mexican Restaurant and Caterers.

THe name is almost bigger than the place, which is only a half-size house and seems to be falling down at that. A soft drink machine and a garbage can decorate the front porch.

The inside is cramped. The few tables wear checkered cloths and the menus spots of hot sauce. The well-scrubbed young people who were eating there the night I visited seemed to look upon the dingy ambience as authentic, dusty border town. The main attraction at Speedy's, however, is the food, probably as close to real Mexican as Washington can come.

We decided to visit Speedy's one night for carry-out because our 2-year-old was sick and unable to go out. I was elected to make the dinner run. Since I was in a hurry to get back home, I dispensed with the several pages of menu - listings of almost any kind of Mexican food a customer might want - and ordered the La Casita Sampler, for $5.95, which had a taste of several things.

I ordered two of them, but the waiter assured me it would be too much food. I also ordered some hot sauce for 60 cents and a Sapopilla, 85 cents, which is a flaky pastry sprinkled with cinnamon and honey. The entire bill was $7.12.

When I got home, my husband and I discovered the waiter was right about the portions. In the dinner there was a beef special taco, a beef crispy taco, a beef chalupa, two burritos, three chiladas, guacamole salad, refired beans and rice. A large bag of tostados (crispy corn chips) had also been included to dip in the homemade hot sauce of tomatoes, green peper and onions. The tacos were stuffed with mounds of spicy ground beef, and the vegetables were crisp and fresh. Unlike much of the Tex-Max food served here, which is mostly past and nondescript, the Speedy Gonzalez offerings were flavorful and well prepared.

Equally good was the pastry, which was as big as a dinner plate and ample for the two of us.

Speedy's, located across from the Parkington Shopping Center, was opened four years ago by a government worker named Ted Gonzalez, we were told at the restaurant. Gonzlez, who grew up in the Southwest, wanted to expose the area to more authentic Mexican cuisine.

Most of the recipes are his own. Originally, Gonzalez did all the cooking, waiting on tables and sweeping up himself. Now he has a crew of young people who operate the place with a more haphazard flair.

On Weekends, the restaurant offers specialties of pit barbecue, made of beef, and tripe soup. On occasion other dishers are also made up, including chicken mole made with beer and spices. Daily lunch specials are available for $1.75.

No credit cards. Personal checks accepted. Open weekdays 11 a.m. to 3 p.m., 6 to 10:30 p.m.; Friday and Saturday, 11 a.m. to 10:30 p.m.; Sunday, 11 a.m. to 8:30 p.m. Accessible to the handicapped.