I purchased it in 2008, new
Mazda 6, Sedan 4d, Automatic, Sport 2.3L
along the time I measured a few times the mileage in the town, about 370 Miles per Full tank.
One month ago, I noticed that I make 310-330 only,
my 30K service happend about 1.5 month ago, they also did

Fuel induction cleaning
Brake flush
Transmition flush
New tires.

Well, coincidence or not, but I noticed the mileage drop 1 week after the service,
I know it's winter time and every morning I start the engine for about 5 minutes before driving the car, to warm the engine and the inside of car so my 7 years schooler feels nice on his way to the school , can this be a good enough reason to loose 50 miles per full tank ?

A simple math shows that I keep the engine started without doing any miles for about 2 hours monthly, time when I also have the seats heating on and air heating on, may this affect my mileage to drop from 370 to 310 per full tank in the town ?

...or it's also possible that service guys screwed something up at my last service, I am always doing the service at a Mazda dealer which sold me the car in 2008.

Thanks.

 

Given cold intake air, winter blend fuel, and your unnecessarily long warm up period (which is very bad for the engine), it isn't at all surprising your fuel economy has suffered to the extent you've experienced.

 

Thank you for the reply, can you please suggest which of my actions need improvement ?
Thanks.

 

The only thing you can control is your warm up period. If you turn your car on when its cold and turn everything to full blast heat, its going to suffer. What I normally do is turn it on and let it run and only just turn on the heated seats. Your HVAC system draws a lot of energy.

 

Start your engine, hop in, and drive; best for your engine and will speed warm-up inside as well.