Bumble,

It is very difficult to control the market value of vehicles, even when there are only hundreds of them on the market.

Ultimately, it will work like this:

At any moment in time, if the quantity of owners who want to sell their vehicles exceeds the number of people who want to buy them, the price will drop until the number of buyers exceeds the number of sellers, at which point prices will rise again. These are the peaks and valleys in market value. Holding out for more money could affect this slightly.

Long-term, you will see a curve with an upward or downward trend. There are many, MANY factors that affect that curve. What you want for your VX is a very minor factor and will not significantly impact it.