Pre or Post 06 facelift?
 

In the market for XC90 not got big budget what are main difference between early cars and 2006 facelift I've noticed the engine bhp is more but also the tax is nearly double. Are the improvements worth the extra tax?

Not quite that simple…. Volvo make changes gradually, the 185 Euro 4 engine arrived before the facelift…

Euro 3 card (163 bhp) pre 2005 model year are regarded by sone as the best XC90s as the engine are super smooth and the most reliable as well as most economical… but the are aged now, good low mileage examples are very rare and not many left with good history.

2005 saw the 185 engine with the improved 6 speed gearbox, although more powerful the engine was slightly less refined and some models had reliability issues with the extra emissions kit - thought they’re still unlikely to leave you stranded.

Then about a year later there was a subtle facelift.

If you fancy the facelift - look for a SE LUX with xenon headlights etc. sat nab was always an option. Lots of buyer guide type posts on here. Watch out for post March 2006 models with expensive car tax bands, as you seem to have noticed.

Personally I would get the best Euro 3 car I could find.