Auto Tech Service, off Ontario Rd NW. Sometimes the people you get on the phone don't speak good English but don't let that turn you off. Took my VW in when it didn't pass emissions, guy who runs the place tried to fix it twice for free to avoid me having to buy a new part. He really cares, very honest, I will never go to anyone else.
Not to mention, highest rated auto mechanic in the DC area on Yelp.