fix car tyre and wind sounds not plaing while going backwards

mods/cars/init.lua

@@ -486,22 +486,22 @@ local function car_step(self, dtime)
 	end
 	self.timer2 = self.timer2 + dtime
 	if self.timer2 > 1.5-self.v/max_speed*1.1 then
-		if math.abs(self.v) > .2 then
+		if abs_v > .2 then
 			if math.abs(velocity.y) < .1 then 
 				self.wheelsound = minetest.sound_play("tyresound", {
 					max_hear_distance = 48,
 					object = self.object,
-					pitch = 1 + (self.v/max_speed)*.6,
-					gain = .5 + (self.v/max_speed)*2
+					pitch = 1 + (abs_v/max_speed)*.6,
+					gain = .5 + (abs_v/max_speed)*2
 				})
 			elseif self.windsound then
 				minetest.sound_fade(self.windsound, 30, 0)
 			end
 			self.windsound = minetest.sound_play("wind", {
 				max_hear_distance = 10,
 				object = self.object,
-				pitch = 1 + (self.v/max_speed)*.6,
-				gain = 0 + (self.v/max_speed)*4
+				pitch = 1 + (abs_v/max_speed)*.6,
+				gain = 0 + (abs_v/max_speed)*4
 			})
 		end
 		self.timer2 = 0