I'm thinking about developing a street rod style game (I know you lot have heard it before

). To get started I'm thinking about the minimum I could do to have a fun game. Hopefully at that point it would have enough interest to attract more developers and start consider more advanced features.
Here are some very general thoughts I have had,
- What made Street Rod unique for me was the race/build cycle. Forza or GT has upgrades but it doesn't seem the same, I think the actual wrenching was significant and buying parts that will go together instead of just checking off a list of upgrades. I probably would keep the complexity of replacing parts similar to SR here.
- Multiplayer, this seems like an obvious improvement and has endless possibilities. It does bring in a lot of additional complexity however. Initially I think it would be best to target either multiplayer or singleplayer.
- Singleplayer would probably be similar to SR1&2, race/build to beat some King dude. I'm not sure it would be fun without some objective but maybe other people have a different opinion.
- Multiplayer would be open ended. Meet up people through some matching system, check under the hood and race if you want. Keep track of stats would give people things to work for.
- Newspaper - I think this is a good format to buy/sell cars and parts but it doesn't scale so well. I think something you can search and filter would be better. Maybe styled to look like craigslist or something.
- Running out of gas - kind of silly but I think it's important.
- Racing - I left this till last because I'm not exactly sure what I think is needed here. It should be fun and your parts need to affect your performance. I think maintaining street racing is a good idea to keep the underground feeling. Maybe a drag strip too like SR2.
I'd be interested to hear other peoples idea about a minimal feature set.
edit:
I think buying tools to enable certain modifications would be important too. Example buy paint gun for painting, wrenches required for almost all mods, floor jack, hoist, etc. This even opens the door to specialized 'mechanics' in multiplayer if the tool cost is high enough.