That's a good question. I think the Ferrari actually was pretty shrewd on Edward's part, but it does seem odd at first. I think it ended up being a statement of flattery to his new wife.
I think it will take a while for Bella to get comfortable with it. She might not get there, though, and end up settling on something more practical. Personally, I think the Ferrari is too flashy, cops sometimes pull you over just to get a gander at your car if its pricey and rare.
First, I think Edward knew he was going way overboard with the Mercedes Guardian, so he went sporty to compensate.
Second, Rosalie has her BMW and Alice has her Porsche. There wasn't any way that Edward was going to get something "practical" for Bella. If Bella wants to trade her Ferrari in for a Toyota (and she very well might), that's fine, she can do that, but he isn't going to stick her in a Toyota to begin with if her sisters have flashy cars. And Edward isn't going to get something "in the same range", he wants Bella to have the best. If she doesn't want to have the best, that's up to her. She can downgrade if she wants, but he isn't going to do that himself.
[BTW, if he had got her a Toyota, what do you think Rosalie would say? I'd bet she would needle her over it.]
Finally, I don't think Edward has any idea exactly what Bella would want. If my arm was twisted, I would hazard that Bella might like something more along the lines of Emmett's Jeep, or some kind of SUV or truck with off-road capabilities, along with being able to haul something around. Bella likes feeling useful, and the Ferrari feels too self-indulgent for her tastes. But I really have no idea. What kind of car do you give to someone who is still mourning their old beat-up truck?
"It will take an amazing amount of control,” she mused. “More even than Carlisle has. He may be just strong enough…the only thing he’s not strong enough to do is stay away from her. That’s a lost cause.”