hey .. my car is a 1997 gsi manual with a exhaust and extractors. It gets roughly 350-370km's for a full tank..which im quite sure isn't right for a 1.8 litre....how much should the integ get 400+?

1. would tire pressure or my car slightly turns the the left could also contribute to this?

2. and i read that the thermostat could also be a contributor to lower km's,

3. i have also read in another forum that someone had replaced their clutch fan which hence improved their fuel economy...i have a fan which sits like nearby to the bonnet latch that fan doesn't move...the previous owner said it was sensered to when it gets warmer it will move...idk but i saw pictures of a clutch fan on the internet and it looks like it is that on my car not moving at all when the engine is on.

4. and if these needs to be check is there any costs that would be involved?
spark plugs
02 sensor
ecu

soz for the noob questions i just bought my first car and just threw in whatever i thought was revelent to others with not so good fuel economy.