Right bare with me on this lol long story, i replaced the coil pack last week on the motor as it was missfiring-all was fine till this afternoon,i finished work & started the car up at 5pm, i was just about to check the oil when i noticed the car missfiring yet again and i noticed a fair bit of thick white smoke coming out of the exhaust anyway i sat in the car and looked at the trip computer which i have on the petrol consumption & it started on 22.5mpg then slowly dropped a mile to the gallon literally every second until it stopped at 10mpg so i drove off home and it raised back up to the 22.5mpg i had before but then when i arrived home and sat there with it idling for a while it started yet again droppin its mpg down again quite rapidly before i turned the engine off! a mate of mine told me to hold my hand up against the tailpipe to see what it smelt of,so i did but it never smelt of fumes/petrol come to think of it it didnt smell off anything! either my car's having a mad 10minutes or theres somthing serioulsy wrong with the car,i dont suppose anyone knows whats going on here???
Any help appreciated