A rediculously hard decision...

Ubetit

Sell the Z and buy a reliable used 4 door sedan. Don't put yourself in financial stress, especially the way the economy is. You have plenty of time to get back into a sports car. Hell, even in 4-5 years they can crawl in the back and get themselves into a car seat. My daughter has done fine the last 4 years with my beater 06 Civic Si coupe.

and birdman is right... just becasue you can "afford" it, doesn't mean it's a wise financial decision. I could afford a much nicer second car than my civic si but it's paid off and it only has 50k miles on. Id rather own my house free and clear in 10 years.