1st ting ya wanna do is put that texmap on the hood as a base color. If yr usin' the Diffuse color as yr paint color, you'll wanna make sure to use a B/W texmap. If yr used a texture mapped color over white diffuse, you'll still wanna convert it to B/W fer later. Next, insert a Math Functions node directally off yr Reflection Value & whatever ya hava attatched (in this case, a Color Ramp). Set the Math Arguement to Multiply, plug the "interrupted" node into Value 2 & set the parameter to 1. Now copy yr main Texture map (or use the B/W one ya made), & plug it into Value 1 of the Math node. The reason fer the Copy is thus; by adjusting the Texture Strength of the map, you can adjust the "flatness" of the paint...full strength = no reflections, no shadows, no nuttin'. Pure black. Zero strength = well...redundant, innit? The point is that even "matte" paint duz give off reflected light, it just ent glossy like a nice shiny car. The reason ya want to use a 2nd tex map instead of simply pluggin' yr main one into the Math Node is that when ya reduce yr Texture Strength, if yr connected to yr main tex yr gonna get color bleed through yr nice black decal. Have fun, & remember to wear yr respirator while paintin' 8-)

WARNING!

This user has been known to swear. A LOT!