It started out at $1,800 in the first half of the year, but then switched to $900 in the later half. That is my understanding, at least, from the tax literature I've been able to locate.

I could be wrong, but I'm 99.9% sure it's $900.00 if you purchased after the middle part of the year.

It's a similar system with most hybrid and other eco-credits. Usually you only get the full benefit if you purchase early in the year.

Depending on your tax rate: an $1,800 deduction could be akin to giving you $900.00+
a $900.00 deduction would be akin to giving you a $450.00+ sum of money

Either way, it's a small credit and not the end of the world.