When writing the book My Garden is a Car Park, I was asked by the RHS to report on a garden in suburban London as part of their 'Greening Grey Britain' campaign. I found a pretty front garden; a straight path leading from street to door, which neatly bisected beds of easy-going perennials (eg hardy geraniums), and fool-proof bulbs (such as alliums). White-flowered Solanum laxum 'Album' grew over the railings, distracting attention away from parked cars. Off to one side of the Edwardian house was the original garage, with parking in front reserved for visitors. The owners' decision to pay for residents' parking permits was a measure of their generosity as well as a desire to make the most of their space. With a small cherry tree by the front window, the seasons could be witnessed in a few minutes every day, between the door and the street.
Over the last decade there has been a dramatic increase in the creation of off-street parking in what used to be called front gardens. One third of these forecourts have no greenery whatsoever. It's clear that this adds to water-run off, putting too much pressure on drains and increasing flooding. Just a tree will help to absorb water (and it can clean the air, while adding shade in summer and insulation in winter). Paving does not have to be impermeable and gravel is an agreeable growing medium for self-seeders.
For my book, I visited a garden in Northamptonshire that has cars coming and going in front of it constantly, as there is a pottery business attached to the family house. The most striking thing about the driveway was the semi-transparent screen of three types of tall wavy plant. The grasses were Stipa tenuissima and Panicum virgatum 'Heavy Metal', joined by felty spires of Verbascum bombyciferum, and airy but tough Verbena bonariensis, with its small purple flowers. Both verbascum and verbena bloom over a long period and have the added value of being attractive to pollinators. Because these plants were happy colonising the edges of the front drive, there was no obvious place to put the cars, except to one side, out of view.