I'm also currently collecting all the models. It's actually not that easy to come up with an algorithm that will not let you miss some of the cars, if you're trying (like I'm doing) to make engine and chassis restoration for all the UCD-cars you buy as well.
My modus operandi was this:
1) Get as much cash as possible before you start.
2) Buy all street cars (i.e. non race-cars) from the Premium Dealership (you will not have enough money to do that, but with the exception of the Miura and maybe the Citroen GT's, that will be enough.
3) Now you start buying all street cars from the UCD. To be able to do this without letting some slip through your fingers, you need a lot of cash per race, so that means b-spec Dream Car Championship is your best bet as it offers the best per race output besides a-spec endurance races, and that would be too gruelling. And even with that, you will be close to bankrupt some of the time. You can save some of the engine/chassis refurbishment for later, if you're short on cash. If you don't restore all cars to prime condition, the money should be plenty and you should be able to even save some cash in the process.
4) The more cars you have, the more cash you will be able to save after each Dream Car Championship and eventually you'll get there getting them all.
I'm still missing about 10-15 non-race cars (NSX-R Road Version, where are you??, Ford GT '02 anyone??), so I can start now with the race cars, which appear much less frequently anyway, so I hope I'll be able to buy them when they come along. I'll probably have to do that in steps though as well. (Buying all below 500,000, then below 1,000,000, etc.)
I'm at 903 cars total now, with about 50 duplicates, so still quite a way to go.
I know, it's madness, but all collecting is. Not doing it for the trophy though, but, when I'm finished, I'll start testing each and every one of them. So, it's for a good cause! ;-)
))))
