I'm going to explain it in several parts, but, first of all, I want to explain a little bit about what it is about.
As you know, cars make a lot of noise and pollution, and is the principal cause of global warming. Because of that, some companies have started making hybrid and electric cars. So, I thought it would be a great idea add noise and pollution to cars. That was the main idea, but, then, i got a lot of ideas related with this.
Having said that, let's start:
GAS STATION
A gas station for gasoline cars & hybrid cars
GASOLINE CAR FACTORY
A factory that makes gasoline cars.
It can be upgraded 3 times:
-Upgrade/Level 1:
Highly Polluting Cars.
At this level, the factory makes cars that makes a lot of pollution and a lot of noise
-Upgrade/Level 2:
Medium Polluting Cars
At this level, the factory makes cars that doesn't makes too much noise and pollution, but stills being far from 0 pollution and 0 noise. It's like a medium level between highly polluting cars and lowly polluting cars
-Upgrade/Level 3:
Lowly Polluting Cars.
At this level, the factory makes cars that have a pollution & noise regulation system.
HYBRID CAR FACTORY
This factory makes hybrid cars
It can be upgraded 3 times:
-Upgrade/Level 1:
At this level, the factory makes hybrid cars with a low reliability
-Upgrade/Level 2:
At this level, the factory makes hybrid cars with medium reliability
-Upgrade/Level 3:
At this level, the factory makes hybrid cars with high reliability
ELECTRIC CAR FACTORY
This Factory makes electric cars, but with one difference.
This one needs a lot of power to work and it's way more expensive than the other 2 factories.
It can be upgraded 3 times:
-Upgrade/Level 1:
Extremely low Reliability Cars.
At this level, the factory makes cars with an extremely low reliability level. That means they need a lot of power and they get without power very easily.
-Upgrade/Level 2:
Low Reliability Cars.
At this level, the factory makes cars with a low reliability level. They don't need that quantity of power and they doesn't get without power that easily.
-Upgrade/Level 3:
Medium Reliability Cars.
At this level, the factory makes cars with a medium reliability. They use a normal quantity of power and they have a similar duration to the gasoline cars.
A station for Electric & Hybrid cars. Needs a high quantity of power.
This is my idea, i know it's a lot of work, but if you want to do a plugin with this, you can

Let me know what do you think!!!
