I can't really give figures, but a 10 year old X5 will cost a lot more to maintain and out of these two I'd go for the Qashqai all day long. Avail yourself of the opportunity to check numerous owner reviews of each car on Youtube and even check this sites review section. You can always input the number plate (from an ebay listing) of one of these cars on Eurocar parts website and compare typical parts prices.

www.honestjohn.co.uk/carbycar/bmw/x5-e70-2007/good/

www.honestjohn.co.uk/carbycar/nissan/qashqai-2007/

Neither are particularly reliable, consider that Nissan are owned by Renault and use a lot of the same mechanicals, both cars you stipulate are only worth having from new under manufacturer's warranty in my book. If it must be a SUV type car, consider a Honda CRV and Toyota RAV4. You haven't stated your preference of diesel or petrol and mileage per annum.

If you want a SUV as such, then as said you won't go too far wrong with Japanese.

Toyota Rav4, Honda CRV, or one of the Mazda equivalents (confess i've not been into Mazdas so don't know the models) or even a Mitsubishi of the type.

Rav 4 will have the balance of its 5 year warranty (after 2009 i believe), not sure about the others.

Korean cars of the type can be good buys too, with a Kia Sportage for example so long as the mileage is well under 100k and the service history perfect (and it must be perfect) then you would still have the balance of that 7 year warranty, the Hyundai equivalent has a 5 year unlimited mileage warranty, again this warranty has to be perfect, vital in both cases it's main dealer history and you have receipts to prove, stamps in the book are not enough because there is big business in the used car market in false service histories.

Your main problem will be finding a petrol engined version, as since DPF issues have raised their ugly heads (and for goodness sake don't buy a Mazda Diesel) more and more people are turning away from Diesel and going back to petrol...Diesel can still be suitable for some people even with DPF's if their motoring comprises enough reasonable distance driving regularly enough for the DPF to clean itself, so many people don't have suitable use and get issues.

Your budget, assuming you want to spend so much puts you almost certainly into a DPF equipped Diesel, so do your research with any potential vehicle.

If you give an approximate location, and your typical use, we already know your budget, there are a couple of posters here who are jolly good at finding some good motors on the usual sales sites, and have linked them for posters in the past, they might if they have half an hour to kill put some suggestions up for you.

Be aware with all of the slightly smaller SUV's, that not all (qashquai for example could be either) models come with 4WD, if you are after AWD that is.