And of course not to forget the front passenger seat. If not needed, it is just a dead weight driving around. Do not forget on the seatbelts.
Climate compressor is also not light.
All the interior door trims and electric window motors would add some weight also. Do not forget on the central locking mechanism, pretty heavy since it is not a light A2 specific part + 4x. Just tape the doors.
After that you can start with sunshades removal. Few grams there.
If you do not care about safety, airbags are the next thing to remove. Not light…
Sound insulation under the engine cover is the next thing to go.
Lighter battery, factory fitted is a large and heavy beast.
Next, radio needs to go (1kg there), you will not be able to hear it anyway. Do not forget on CD changer (if the car has it). When you are there, just rip all the audio related harnesses and cables. Should be at least 1-2kg in there.
Front passenger storage compartment: half a kg at least.
A2 sign at the back and 4 rings at the front are just fuel guzzlers. Do not forget to tape the holes.
Fuel up only to half or even less. 20 kg saving there.
Take a scotch tape and tape all the opening on the car.
And for real fuel savers: every time you go to drive the car, you need to go to the toilet and take nr. 2.
Not to forget: tire pressure up to 4 bars…
OMG
Seriously: just lower the speed and you will get much better mileage. I usually drive on motorway on acc set at 95km/h and i get aroung 4 l/100km (70.6 mpg) with Octavia 2.0TDI DSG. Removing interior trim will add noise to even now noiser TDI in A2, thus leading to higher fatique and less safety to all. Skinier (but legal) tires are definitelly the option, also check that engine and brakes are in perfect condition. This can quickly lead to higher fuel consumption.