Same sort of thing happened to me, 3 litres of massonary paint in the front passengers foot well (total bellend thing to do), went in to a roundabout and over it went, I was on a dual carriageway so had to carny on a bit. Every time I braked I had to watch a wave of paint go up the front of the foot well.
I cleaned it out best I could then sprayed the carpet with black spray paint! Could hardly notice it, except the carpet was a bit crunchy.