From his previous posts I would suggest he doesn't have the budget for an SRT6
To answer the original question, I have an SRT6 Roadster and as you may know the SRT6 only comes with an Auto box and I last averaged 23 MPG
I did not look at his previous post but see below link for a SRT6 roadster for sale in the UK. I guess a Coupe will be even less expensive.
Chrysler Crossfire 3.2 V6 SRT-6 2DR AUTO MASSIVE SPEC 2006