Amazing milage swift vdi

I bought Swift VDI in july 2009. so far the car cloaked around 27000 kms and is driven by me only. Normally this car is used for cross country drive. That is from my place of work to permanent home town. I am not a professional driver. But due to swifts comfort, I cover around 900 Kms in a day. Around 15 hours of driving including two 45 mins brakes. Recently, I drove my car in heavy rainy condtion where i didn't dare to go above 85 kmph throughout the journey of 900 Kms in a day. Amazingly, I got milage of 26.2 kmpl with AC on with four occupant and luggage weighing around 50 Kgs. Normally i used to get only around 24 kmpl with the speed of 100 kmph. I'm a mechanical engineer. I hope that higher relative humidity in intake air might have caused the trick. Can maruti look into this humidity factor to improve its milage factor permently.

Arumugm M