I don't even know who makes infinity or if that is the make.

u need 2 cheak the hoses for cracks but more importantly cheak see if the timing belt/chain has been changed. its supposed 2 be done every 100,000 miles

It depends on the type of Infiniti you are talking about =)

Infiniti is Nissan's premium brand. Every Infiniti is a dressed-up luxury Nissan of some sort.

Generally, they are very very good used cars. The i30 is the same thing as a Nissan Maxima, which is an excellent choice for a powerfull used sedan. It will probably require a little work, as they tend to need new injectors or at least an injector cleaning around 100k miles, but the engine and transmission are very stout. I worked for a Nissan dealer service dept and I saw them in with 200,000+ miles weekly.