Don't do it. Don't go for the 150. Why? Because this particular guy here stumbled upon your post (and this whole board) by being totally annoyed having ordered one. I registered just to tell you that you really shouldn't go for it. Rant follows:
I received mine (A3 Sportback, quattro, 110kw/150HP, manual, S-Line, more or less all options ticked off) on the 14th of June as my company car - and I would return it, if I could. Everything about the car is great (looks awesome, materials are great, manufacturing is amazing), but I hate driving it. It's a dog. I'm currently averaging 14l/100km, Diesel mind you, - and it's really, really feeling like crap. There's no way to drive it without putting your foot down to the metal (and because I've ordered the car with drive select, I even have a 'kickdown' kind of switch at the end, that won't do a thing unless you're running in eco-mode, further reducing the already crappy performance. Nothing nags me more than that switch that I'm constantly pressing by accident (because.. if I don't hit the pedal hard, the car doesn't even move..), doing absolutely nothing. Except increasing the frustration about the lack of any fun/performance at all.
My previous car was a Golf GTD - that was really fun to drive. But this A3 isn't even in the same league. I'd bet that a Ford Ka or whatever small car you can come up with (VW Polo? Anything from Hyundai even..) is more fun to drive. I _hope_ the 135kw option makes the car acceptable to drive, I really cannot know. But the 110kw variant is a huuuge disappointment, not worth the money.
Driving on the German Autobahn is an exercise in patience and I usually feel like a moving obstruction in a 53.000 EUR car that looks like it should be able to run along, but really cannot. It's promising a lot and can do very little.
It's so bad, I have the feeling it was conceived on paper and never driven as a prototype. It ruined all my respect for the 'quattro' label and a good deal of Audi's reputation on top. I don't gain a thing by ranting here, but please.. Take one out, do a test run and feel for yourself. I ordered it without sitting in that model before. My fault, don't do the same.