Mog – both the 2.0 petrol and diesels are good; you may find the petrol a little under powered when fully loaded.
A 2006 E90 320d will be the 163PS engine; modified swirl flaps so no need to worry in this engine – turbo can fail but that is the same for any car and is dependent on servicing and how the car has been treated. If you find the fuel consumption is poor you can go into the “secret” menus to check the engine temp; the thermostats can degrade which lead to the engine running at 80 degrees rather than 90, this hits fuel economy, particularly in the winter. £200 to replace at an Indy.
The 320d changed to 177PS in Sept 2007; there have been some reports of timing chain failure on these engines but it is one of the most common engines fitted to BMWs.
In late 2008 / early 2009 they gave the 3 series a face lift and in 2010 the 2.0d went to 184PS
Both of mine have been M-Sports and I’ve got decent mileage out of the tyres (30K per set)
Things to look for when buying – check the service history and when the next services are due on the computer as everything is condition based; third oil services on the diesels are expensive as the filters need to be changed.
My wife’s 2006 120i was recently serviced at an indy and was £370 for almost everything (oil, filters, plugs, brake fluid, inspection) – first money we’ve spent on it in 2 years.
If the tracking needs doing I really recommend the £150 wheel alignment at BMW; I’ve had it done by an indy for £30 in the past and it ruined the handling – when setup right they don’t eat tyres and the handling is spot on.
Standard kit is generally good on the SE but if you can look for one with bluetooth.