accelerateCar fixed

void accelerateCar(double delta_speed, double target_stable_time, double speed_increment, double final_RPM, )
{
	double speed_difference = abs(current_RPM - current_RPM1);
	double speed_band = current_RPM - current_RPM * delta_speed;
	if (speed_difference <= speed_band && current_RPM >= first_target_RPM && current_RPM <= final_RPM)
	{
		if (stable_speed_reached == 1)
		{
			target_RPM += speed_increment;
			stable_period_entered = 0;
		}

		else if (stable_period_entered == 0)
		{
			initial_stable_time = millis();
			stable_period_entered = 1;
		}
		else if (stable_period_entered == 1)
		{
			if (millis() - initial_stable_time >= target_stable_time)
				stable_speed_reached = 1;
		}
	}
	else
	{
		stable_period_entered = stable_speed_reached = 0;
	}
}