I just did the math for my S2000 $56.13 in parts
6 qts of Mobil1 5W-30 @ $8.19 ea from Autozone online today
Filter Fram @ $6.99
4,000 mile change interval
Cost per mile = 1.4033 cents

And for the SRT-6 $86.20 in parts
9 qts of Mobil1 0W-40 @ $8.19 ea from Autozone online today
Filter Fram @ $12.99
7,000 mile change interval
Cost per mile = 1.2314 cents

Surprisingly, the SRT-6 is about 12% cheaper per mile because the 54% higher parts cost is more than amortized by the 75% longer change interval. Obviously, the answer changes if you can get one oil or filter for a lower price. But the real lesson is that the SRT-6 is not much different from other cars and possibly slightly cheaper.