Part of the problem is that a lot of people think they need every single gadget that's been invented to be included in their car. As long as people are demanding certain items Ford, and other manufacturers, are going to find ways to include them. Sequential turn signals, adjustable effort steering, factory line locks and launch controls all cost money to develop. Until people realize that they don't really need so many gimmicks on their cars the price will continue to rise.
Then there's the safety and fuel economy mandates from the federal government that continue to fuel price increases as well.
Part of that issue is that other cars offer many of the new "electronic features" with little or no additional charge - the actual cost of that technology is very very low (Due to the volume manufacturing and the price performance improvement of electronics overall).
The Mustang charges a "very high up-charge" for the new electronic features.
2013 Mustang GT Premium Convertible
Candy Apple Red, Auto, FRPP Tune, GT500 Axlebacks, KONI Yellow Sport (adjustable dampers), FRPP Front and Rear swaybars, Custom Removable 4 Point Roll-Bar, BOSS 302 Low Expansion Brake Lines, Roush side splitters, GT500 spoiler, Redline Tuning hood struts,18" Ford Chromed Aluminum Wheels (9R3Z-1K007-A), Michelin Pilot Super Sports - 235X50X18
2011 Mustang V6 Premium Convertible - Gone