If this is a petrol car, I assume there's no turbo, so the outside air goes through the filter, through the airflow sensor, through a throttle assembly and into the inlet manifold. There's nothing to heat the air on it's way through, at least, not that I can think of. What about the external air temperature, is that reading OK? What are you using to generate those gauges, because it doesn't look like a standard Hyundai display. Could it be something as obvious that the sensor output is being converted to farenheit, and displayed as farenheit, even though the meter scale is celcius? As you're in Greece, and it's hot, those temperatures could make sense in farenheit.