Replacing my RCA's with some quality ones and my choices are 6m or 4m. I'm thinking 4m will be fine, routed under the sill plate/carpet on drivers side but the price difference isn't much. I'd prefer not to tuck an extra 6ft of wire under the seat.

3.28 feet in a meter

4m = 13ft
6m = 20ft

Money doesn't always bring happiness. People with ten million dollars are no happier than people with nine million dollars ~ Hobart Brown