In Northern Virginia, as far as I can tell, almost all of the stations are selling 40 cetane diesel. BP used to sell 45 cetane. My 1985 300D ran quieter, smoother, maybe with more power on the 45 cetane than it does on the 40.

There is a BP in Tysons Corner that sells 50 cetane. At $2.99 per gallon, it's pricey, but it makes my car run great.