Trading in your rav4 for a Q5?
If so the Q5 will feel like a better quality cabin but expect less reliability that's for sure.
If you only do 5k miles a year then you'd be better off with a petrol. As that little mileage per year can clog up the dpf with soot and clog up the egr. Both of which are over £1k each to change.
Have a look at buyers guides on YouTube.
Make sure all electrical items work and check the service history.