It's in the garage? So you're not using it? Sounds like you could improve your hardware utilization. You should drive it somewhere.
If you don't have anywhere to go, it's not under-utilized. There's no reason to operate it more than you need to. A resource is only under-utilized if you have a legitimate use for it, but aren't.
There are several stages to developing software. Only when we have a release candidate can we test the product (before that, we don't have a product). So there are significant lengths of time during which equipment will be idle and periods in which it will be in great demand. During idle time, our engineers should focus on reducing their automation backlogs or plugging testing gaps by writing new test specifications, investments that pay us back repeatedly.
We shouldn't contrive uses for our testbeds any more than we should contrive uses for our car. Write a test plan and execute to plan. Creating make-work is wasteful. The worst sin is to waste human resources in trying to make hardware look busy. People are more expensive. Let's make their time count.