Thats great! Nice looking render. I love this design, btw. Very cool...the car is a perfect fit here, too.
Are you using light dome/HDRI or Vray sun to light the scene? If light dome/hdri, you can up the texture resolution from 512 up to 2048 for some more GI quality. (at the cost of higher render times, of course
With low light renders such as this, you're always going to need higher settings to reduce noise...and longer render times. Although there are tricks to getting around this which happen in post.
From here you can save the render in frame buffer history, then do small render regions on problem areas while tweaking one setting at a time to figure out what works/helps and what doesn't. So, depending on what renderer/GI method your using, you may try upping the min shading rate a bit or lowering the noise threshold if using brute force. Or if using Irradiance Map, try raising Quality subdivs and/or Irradiance map subdivs. If done correctly, your region renders should merge with the whole render, if not, just save them all and smooth out the seams in photoshop. Unfortunately, the denoiser passes when using render region leave the rest of the render outside the 'region' black....so they have to be composited in post...hope they fix that soon. Let me know if you have any more questions about anything. Good luck and have fun!
On a side note - if this were my project, I would like to see how things look with the architecture lit up more. Maybe more exterior lighting to really accentuate the building. I like the mood you have here, but overall its a bit flat. More lighting like you have around the base structure could really make things pop.
cheers!
