Over and Under Designing Vehicles.

The game has two design penalties that may catch some users off guard.  These penalties are for over-designed and under-designed vehicles.

Slider positions cause both issues, but they penalize you in different ways.

If too many of your sliders are to the right, I.E. better, then the designer will start to increase costs exponentially. The more your sliders are to the right, the more the exponential value increases. This increase is to simulate hyper-car designs. As the saying goes, you get what you pay for. If you’re trying to create the best vehicle ever made, it will be very expensive.

At 100% sliders, this vehicle design's material cost is $25,182. 

Dropping the sliders down to 50% reduces the price by 26%. 

Decreasing the sliders down to 25% would only reduce the material costs another 4%.

It does not cost as much to double from 25% slider to 50% slider as it does from 50% to 100%. Therefore your best rating to price ratio is somewhere in the middle.

On the flip side, if too many of your sliders are to the left, I.E. worst values, then your buyer rating will receive an extra penalty. This penalty is to prevent exploiting the game and to simulate minimum consumer desirability.

In this case, because of the low sliders, the buyer rating of this car had dropped by 42%, from 3777 to 2190 points.

You’ll find designing vehicles, much like real life, is a compromise. You might want to produce the best vehicle ever made, but it would be way too expensive to sell. Likewise, you might want to create the cheapest vehicle ever, but the penalties to the buyer rating will kill sales of that design. The compromise is to balance making the perfect car with making the cheapest car. 

Just good enough and cheap enough to sell well.