Salesforce has two different desktop user interfaces: Lightning Experience and Salesforce Classic. This article is designed for Salesforce Classic.
Open a Sales Up
Begin by opening or creating a sales up record.
From a quick glance at the record you can tell a Desired Vehicle has not been attached. The name Sales Up: Ty K does not display a vehicle description and the Desired Vehicle related-list shows  vehicles attached. It is important to check both.
A vehicle description will only display in the Sales Up Name when the desired vehicle it is in stock. When the desired vehicle is entered manually and the vehicle is not in stock, the related list will show  but the vehicle description will not display in the record's name.
Add a Desired Vehicle In Stock
Locate the Desired Vehicle section below Sales Up Details. To add a desired vehicle currently in stock, double click the Stock# field to open the in-line editor. Hand enter or paste the Stock#. If you click outside the Stock# field, the unsaved data will display in orange as a reminder to save before leaving the page.
Click Save to record the Desired Vehicle.
Once saved, available fields from the Vehicle Inventory record will automatically populate the related Desired Vehicle section.
The Lead Name will now display the vehicle description and the related-list will show Desired Vehicle .
Search using Vehicle Description
It's not likely you memorize stock numbers. That's why the Stock# look-up field allows you to search by vehicle description.
Double click the Stock# field to enter the Year, Make, or Model and click the search icon.
The lookup results will display in-stock vehicles based off the search description. Click on any of the vehicle hyperlinks listed under description in the search results.
Once you have selected a vehicle from the search results, it will be added to the Stock# field in the Desired Vehicle section.
Click Save to add the desired vehicle to the Sales Up record.
Add Multiple Desired Vehicles
Hover over the Desired Vehicles related list. Keep the cursor in the display box and click the button New Desired Vehicle.
A Desired Vehicle Edit window will open. The lookup for Sales Up will be pre-populated by the related record. The vehicle inventory lookup allows you to search in-stock vehicles by Stock# or Description. The manual input fields allow you to record a desired vehicle not in stock.
Click Save to add the additional Desired Vehicle to the Sales Up.
After a second vehicle is added you will be directed to the Desired Vehicle record. To return back to the Sales Up, click the hyper link.
Hover over the related list Desired Vehicle  to see both vehicles are listed. The desired vehicle that is saved to the lookup field Stock# on the Sales Up will always be the primary. It will become the vehicle that gets pulled into a Deal. To replace the primary desired vehicle, simply input a new Stock# in the Desired Vehicle section and save the Sales Up record.