I agree with and will echo TerminatorX5's eloquent statement about 'M' as a lifestyle and attitude, not practicality or economy....

Since your wife already has a X5 SAV, why not consider what ard is suggesting.... Test drive a BMW M4, M5 and M6 and see what it is like really fun rear-wheel driving M cars.

Good luck
AVB-AMG

__________________
My current & recent car history:
2020 BMW 440i xDrive Coupe (Wife's daily driver)
2016 BMW X5M (My daily driver)
2014 BMW M6 Coupe (gone)
2013 BWM 335i xDrive Coupe (gone)
2011 BMW 335xi turbo coupe (gone)
2007 Mercedes-Benz ML63 AMG (gone)
2007 BMW 335ci twin turbo coupe (gone)
2004 Mercedes-Benz E55 AMG (gone)
2004 BMW X5 4.4i (w/full Aero Kit - gone)
2001 BMW X5 4.4i (w/full Aero Kit - gone)
2000 Mercedes-Benz E430 Sport (gone)
1961 Mercedes-Benz 190SL (owned for 48 years)