[Piwoslaw]

Welcome to EcoModder, Radics

Originally Posted by radics1

The car does constantly around 5.1L/100km (46MPG US) on diesel,weight is around 1350Kg.

That's not too bad, but I'm sure you can do better: Your Audi has a smaller Cd than my Peugeot (0.31 vs. 0.33) and less frontal area (at least 10cm lower, even without the 40mm lowered suspension), so you should be able to hit 4.5 l/100km, or even below 4.0.

Originally Posted by radics1

Previously it was fitted with a 1.8T gasoline engine,with pulse and glide i got it to 6,1L/100km also,so it could work also with the diesel engine as well.

So you swapped a TDI into a gasser? Or did you switch cars?

Originally Posted by radics1

I read here also if the alternator is shut down,it also improves the fuel consumption by 5-10% wich would be amazing.I am looking for a solution to use some type of management for the alternator. For example charge only if voltage drops under 12 or 12.2V, Charge on overrun braking etc.
Maybe somebody did this before me.

There lots of threads on this, but I don't think that it has been successfully DIYed. Here is a great read:
Automatic alternator cut out/regen braking
There are a few things you need to take into account when doing this mod:

1. Your alternator has to have a field wire. Some alts are self-exciting, which would take a lot of work to deactivate the field.
2. You must reduce your car's electric needs to a minimum. For example, if you have to have your lights on during the day, then install LED daytime running lights (DRL), which should save 120-200W.
3. You need a large battery, deep cycle is best, otherwise it'll die pretty quickly and the replacement will cost you more than you saved in fuel.
4. Disabling the alternator's field saves some fuel, but not as much as taking it off the belt.
5. You should have a place to charge the battery when parked. Charging it only from the alternator won't save you nearly as much fuel.