"affording" it is different that 'wise financial move'
If you do not own a home, THAT would be my top priority. IMO the market is at or near a historic low. (You say 'no debt' so I assume no mortgage?)
(My first luxury car was a new Infiniti Q45..paid cash. I was in a start up company that was doing well. And ultimately went public)
I tend to buy high performance/quality/feature items and hold them a long time. If you lease cars for three years, you are paying 50% of the cost and will never own it. I can buy a car, hold it for 10 years, put 200k on it- in that calculus, the annual cost of owning an X5 over say a pathfinder is much less...AND the enjoyment higher. In your situation, with an X5, after 4 years it will be the kid/family hauler- then you buy a new 4 dr sedan..then in 4 more years you replace the X5. Car will be 8 years, 120k miles(?) and you'll have extracted maximum value. And you could even make it a few years without car payments if you had to. IMO having one car paid for is essential for a working family.
PS Also like the idea of buying lightly used cars- allow people that MUST have the new toy pay the 50% depreciation!
Keep it as simple as possible...but no simpler.