A fire truck is a fire truck... yes or no? If they meet the standards you put together, and if you are forced to go to bid, this is the mentality you will have to face. Extra's? I don't think so... Unless you have a mega-budget, and I should qualify that this is my opinion solely... If you are going to buy a new piece of fire apparatus, and you want to get an engine that has already been well thought out, it makes absolutely no sense for one to "re-invent" the wheel. Larger departments have a lot of clout when it comes time to buy fire apparatus. Why? Here's a great example...
Years ago, I took a National Fire Academy Apparatus Purchase and Maintenance course. The instructor went on and on about how his department spec'd out a new fire engine. The guy next to me snickered and whispered to me, "give me a break, I just got done ordering 75 engines...".
When a department orders that many engines, I can absolutely assure you that the damn thing went through months of committee meetings, research and work before the final design was settled. If you can live with the standardized approach to neighboring larger departments, you may find yourself saving literally thousands of dollars. Not only will you save money but you will have an engine that was designed by, (example) Los Angeles County Fire Department.
Here's where the problem lies or at least this is what happened in SoCal. The concept of piggy backing your purchase with a larger purchase was networked between several departments. The term "consortium" popped up and the next thing you know all the other fire apparatus manufacturers lobbied for (might have gone to court) all the manufacturers being able to be involved somehow...
My department ended up purchasing eight engines at first and then another seven the next year, all in association with LACOFD. And we got a killer engine that has some very well thought out features, some we never even considered. Without having the hassle of negotiating with your bean counters, the fact that you are saving thousands of dollars is very enticing. This is what we ended up getting... nice ride, eh?
LACOFD - KME Predator Type I Fire Engine
We saved even more money by not having the engines painted red. Instead we received them with a white color and reflective blue strip. It's no different that LACOFD's engines. There is an added bonus. When we respond or they respond to an incident, we are all familiar with each others engines... this is a good thing!