What do the aero boys think?
A look at the USA Ford Mustang website gives an interesting snapshot of engine prices.
The cheapest is 3.7 V6 as in the roadster.
Then the 2.3 EcoBoost a derivative of the +4 GDI.
Then the 5 litre V8 some $10000 more.
Appreciate there will be other differences but power outputs are not that far apart.

Titus

2007 +4 4 seater
2017 Mini Cooper
2007 VW Camper
1996 Honda TRX300
2012 Husqvarna 216