As a Roblox developer, it is currently too hard with my current skill set to create vehicles. Two years ago Roblox released a set of endorsed vehicles to show off the power of attributes however they only came with a limited selection of land vehicles while the demo playground has a wider selection including airborne vehicles. I would like to use those, especially the helicopters.
If Roblox is able to address this issue, it would improve my development experience because I could make up for the skill set I lack as well as use the selection of endorsed vehicles that are not only fully programmed but can be tailored to suit my needs through replacing the chassis and re-rigging the existing code. This can cut my development time in half as well by using already-created content.
The vehicles come from New Endorsed Models in Toolbox!. It seems there were plans to release a second line of vehicles (some developers were asking for the helicopters as well) but there was no ETA provided and it seems to have been silently dropped as a plan. That being said, taking a look at the Main Source place shows that there are unreleased endorsed vehicles.