Colloquial translation

http://it.bab.la/dizionario/inglese-italiano/flat-out This has a lot of suggestions depending on context - I think I'd be inclined just to use 'a pieno' (thhough not for anything to do with a car!)

Driving 'Normale' if you want reckless,driving like a looney. Well that's the Norm for round here.

You could just say “... X guidava come un pazzo”. When we were kids and were driving along at my dad’s quite sedate pace, if ever we got overtaken by a madman, which was quite often, my dad had two sayings: (a) “corri, corri che sei solo” meaning that, since the person was driving so fast there was the risk of an accident, he obviously (and it was always a he) had no family to worry about him if he came to an untimely end! And (b) “Perchè corri, hai paura che ti si fredda l’insalata” fredda standing for raffredda, and meaning “why go so fast are you worried your salad will get cold?”

Funny - a male acquaintance always swears that his 'bumper magnets' are wimmin! Mine are probably 80'% male! But - you have to understand 'car language' - much the same as body language: if you personally are driving sensibly (in your opinion, which I share, like leaving a couple of car lengths between you and the car in front) this is an open ivitation to your bumper magnet to overtake. So just let him/her do it - it's their decison, not your problem. Just don't beef about it. I find Italian drivers (given that I let them overtake and it doesn't bother me) generally far more considerate in urban situations. You dive out in front of them and they give way - only because to avoid gridlock they know they must dive out in front of someone else and expect them to give way. None of the agressive brit behaviour; and in Italy you use the horn properly - as a warning/alert, generaly appreciated by other drivers, and not seen as a reason to headbutt you!