You really think so?
OK, let's crunch some numbers.
Assuming these grown up children run a £28000 Golf GTI, pay £3000 a year on insurance and servicing, and change it every three years, losing 50% to depreciation each time.
They drive 12000 miles a year at, what, 30 mpg and fuel at £6 per gallon - £2500 a year.
I make that £10500 a year. That average house price is £ 220 000.
That's at least 20 years of not running a car to buy the house, on my somewhat exaggerated figures.
Assuming that house prices don't go up faster than you're saving. Which they do.