Nice choice of luxury. I own the same 740 239,000kms and a 1994 960 144,000kms.
The 960 timing belt must be changed at the proper interval,not doing so can cause major damge to cylinder head and vales also perhaps piston parts. So far I've been lucky both mine have had regular maintenance with the usual brakes,exhaust,tires. The only major thing was Ac work to both and so far the 740 in all these years only needed a hall sensor and one relay for the rear light section. My 740 on rough roads rides far smoother than than the 960 maybe I need something for it. There is less leg room for rear passengers. The 960 has a much more bullish engine, it ripes roars and snorts when when you need it. I agree fuel economy is better on the 740 but who cares hence my login name. The 960 is great all around car but if you drive on snow make sure you get 4 winter tires otherwise you you'll be in the bush,dictch what ever you get the hint. Buy it and don't look back.

I just purchased a 96 960 wagon (965) and it is the best highway car I've ever had...smooth as silk. Drove 400 miles without stopping (did not get fatigued or get any aches and pains despite bad back and knees). Fuel mileage not as good as the 740 (I get about 26-28 mpg hwy at 80 mph in my 740 wagon but only 23-24 in the 965) and the car does not seem to be a "nimble" in city driving (it outweighs the 740 by several hundred pounds). Still, best Volvo in our fleet (245, 745, 944 and now the 965). Check out the tips in the FAQs before you buy. Good luck!

This is one subject that has been discussed many times. You can search in the 900 as well as the s/v90 forums for a few months back and get lots of good information. Only one engine in those cars, a 2.9 inline 6 that from what I am told has Porsche design influence. Very smooth engine and car, requiring more maintenance than the 4 bangers but not bad oveall. Most folks love em, some don't. I have over 180k on mine and it is pretty much on original everything. I would recommend them.
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97 S90 with 180K miles still going strong

Check here for starters http://www.brickboard.com/FAQ/700-900/BuyingUsed7xx.htm
Also check the other 960 specific sections in the faq'a, the rest of the car is pretty similar to your 740
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '82 Mercedes 300SD