I like the idea of project cost exponentially increasing or decreasing with time or complexity, but effect of design time on project cost I feel needs to be balanced.
Using a landaulet circa 1925 just as an example as it's one of the longer, more costly projects:
With all sliders in the middle the project takes 12 months and costs $1,567,000
Dropping the development pace all the way down takes the $1,567,000 project into a $236,000 project (roughly 15% of the cost) but extends the project out by just four months. I just feel that's far too much, 15% of the cost for 125% of the project time.
If we take middle of the slider as the "default" pace, I think we should be able to slow a project down far more for much less savings. Realistically, you'd never be able to reduce a project cost by 85% by just increasing the project time by 25%. More realistically, I think it should be perhaps up to 50% savings for doubling the project time.
The other way of looking at it, would be the "default pace" is the bottom of the slider. I don't think that's the case though as (a) it defaults to the middle and (b) that's where it seems to be best balanced in terms of project cost at least early game where you're actually constrained by money.
The other half I feel needs to be addressed is the increase in cost with project complexity. Taking the same landaulet and minimizing all the sliders results in a design cost of $1,101,000 and a project time of three months with design pace in the middle (or 5 months, $162,000 with it all the way down). I think the cost should be more linear in relationship with time. If middle of the road all sliders 50% project costs $1.5 million and takes 12 months, a minimal grab everything from the parts bin and send it out the door with not testing project which takes only three months should cost more in the line of $375,000 (25%), perhaps even less than that. Incidentally, maxing all sliders takes the $1.5 million project and turns it into a 23 month project which costs $4.4 million (or 30 months and $600,000 with design pace minimized).
What this all means is that project cost is really a non-factor as is. All you're concerned with is the unit cost of the design. You can take your obsessively detailed $4.5 million (1925 dollars) design and just by extending the project a few months have it cost less than the grab whatever off the shelf and send it to the dealer. Yes, it takes time (30 months versus 3) but it should never cost less no matter how long it takes.
Using a landaulet circa 1925 just as an example as it's one of the longer, more costly projects:
With all sliders in the middle the project takes 12 months and costs $1,567,000
Dropping the development pace all the way down takes the $1,567,000 project into a $236,000 project (roughly 15% of the cost) but extends the project out by just four months. I just feel that's far too much, 15% of the cost for 125% of the project time.
If we take middle of the slider as the "default" pace, I think we should be able to slow a project down far more for much less savings. Realistically, you'd never be able to reduce a project cost by 85% by just increasing the project time by 25%. More realistically, I think it should be perhaps up to 50% savings for doubling the project time.
The other way of looking at it, would be the "default pace" is the bottom of the slider. I don't think that's the case though as (a) it defaults to the middle and (b) that's where it seems to be best balanced in terms of project cost at least early game where you're actually constrained by money.
The other half I feel needs to be addressed is the increase in cost with project complexity. Taking the same landaulet and minimizing all the sliders results in a design cost of $1,101,000 and a project time of three months with design pace in the middle (or 5 months, $162,000 with it all the way down). I think the cost should be more linear in relationship with time. If middle of the road all sliders 50% project costs $1.5 million and takes 12 months, a minimal grab everything from the parts bin and send it out the door with not testing project which takes only three months should cost more in the line of $375,000 (25%), perhaps even less than that. Incidentally, maxing all sliders takes the $1.5 million project and turns it into a 23 month project which costs $4.4 million (or 30 months and $600,000 with design pace minimized).
What this all means is that project cost is really a non-factor as is. All you're concerned with is the unit cost of the design. You can take your obsessively detailed $4.5 million (1925 dollars) design and just by extending the project a few months have it cost less than the grab whatever off the shelf and send it to the dealer. Yes, it takes time (30 months versus 3) but it should never cost less no matter how long it takes.