If you want the diesel motor, the e70 is the only option to get a newer car. Otherwise I suspect the new X3 is closer to the e53.

I got the e70 diesel after owning two V8 e53s for a couple of years. The e70 is absolutely no comparison for the e53 V8s. You have to buy it on its own merit......

We are very happy with the 35d, it is a very comfortable highway cruiser but I still enjoy my e53 a lot too.

__________________
2003 4.4i black ext./black int./black headliner (kid's runabout)
2014 535d X-drive, M package, silver/black interior

Sold but not forgotten:
2009 E70 35d, black ext./black int./black headliner (sold 2021)
2006 4.8iS Le Mans blue/cream int./black headliner, SOLD in 2012 sadly...

Other hardware:
2015 Cayenne S (wife's new DD and definitely wroooommmmm)
2016 Tundra 1794 edition crew cab, luxo hauler
2005 Tundra crew cab, weekend hauler. Sold after 150k very happy miles.