The crash took place in Framingham, Massachusetts on Monday evening.
The 28-year-old actor was pronounced dead at the MetroWest Medical Center hours later.
Besides his role in "Girls", Lashaway also appeared in the movies "The 40-Year-Old Virgin", "In Time" and "The Last Song" opposite Miley Cyrus and Liam Hemsworth.
Richard Shepard, who directed Lashaway in the 2013 episode, has added his tribute, tweeting: "Sad news. Nick Lashaway who was so great in my GIRLS ep 'Video Games' has died at 28. Funny, sweet & talented. RIP."