I had a 52 plate jdm import with 96kish on the clock, had a full service, new clutch/fly/belts/spark plugs etc etc and a full valet and felt like new. That engine, as long as its looked after will double the mileage. Plus, if you were to crank it up to 150,000 miles, your not going to loose TOO much money on the depreciation side of things. So what I would do, is keep your money in your pocket, save up then buy a GT-R if you want something quick for the road, or if you want a bit of luxury an e class or similar, and keep the 350z and turn it into a track monster so you can have a blast on the track. Well.....That's my plan anyways.