As far as the law goes, the class 4 felony is the maximum sentence for throwing an "object" at an occupied vehicle.
The way laws work in VA, and most other states/commonwealths for that matter, is like this. The legislation writes the maximum penalty into the code. It is then up to the prosecutor and the judge to exercise judicial discretion and impose a sentence somewhere between not guilty and up to the maximum sentence.
In the ice cream case
, the woman only got 6 months. She could have done more than a year. I believe the situation there was that the other driver complained that his vision was impaired and had to cut across the freeway to pull over.
As for spitting, that's also a "missile". Let's pretend that you have amazing range and somehow manages to hit the driver in both eyes. The driver crashes into a school bus = 50 dead children.
I think the legislature wanted to take these situations into account so that even when small and seemingly harmless objects are thrown, the judge can decide how severe the penalty should be.
Also, 25+ over the limit or over 80+ is considered reckless = max $2,500 fine + 1 year in prison.
I have never seen anyone get the maximum sentence, just like I have never seen anyone get the maximum class 4 felony for throwing a missile. These penalties are on the books as a deterrent, and are mostly reserved for really severe cases.
Of course sentencing is always at the judge's discretion and depend on other factors.
But the general rule of thumb still hold. Don't throw anything at anybody, even if you think the object is harmless. Otherwise, you'll have to throw yourself at a judge and his/her sentencing guidelines' mercy.
AFAIK, giving the bird is still ok
, but not at a government official. That's harassment and verbal assault. Who knows.