http://www.carsurvey.org/model_Volvo_S70.html

http://www.epinions.com/auto_Make-1999_Volvo_S70/display_~reviews

http://www.google.ca/search?hl=en&ie=UTF-8&q=volvo+s70+problem+review&meta=

http://www.google.ca/search?hl=en&ie=UTF-8&q=volvo+s70+problem&meta=

Firstly, the 2.0 10v is cheap cos its the engine to avoid. It really
struggles to propel the car at any more than sedate speeds and is heavy on
fuel. 2.5 10v is the best all round engine with manual box, if you want an
auto go for the 20v version.

Our 2.5 10v manual is averaging 32-33mpg in mixed driving- our previous
2litre 20 struggled to do more than 30mpg in the same circumstances.

Would help if you said which model of S70 you are looking at, and what price
its at- it may be a base spec S model, but known issues are:

1) air con generally up the spout, evapourators leaking (dash out job),
rotted condensor, or compressor clutch knackered.
2) Drivers door check strap or top hinge pulling away from body- if caught
early enough (listn for clicking when opening door) and mig-welded up then
gives no more trouble.
3) Engine should start immediately hot or cold and not have any noisy
hydraulic lifters. Oil should be changed every 5k.
4) Look for evidence of timing belt change- 70k. If no proof budget for
changing it (?250)
5) Drivers door leccie window switch panel switches wear out rapidly -
usually drivers door- and suddenly you wont be able to wind up the glass.
New switch units are ?80 from Volvo, good used ones like hens teeth.
Switches from C70 are not the same.
6) If  manual look for clutch noise, and /or biting towards top of travel.
?400 to change if worn out- though they usually last 80k at least on the non
turbo's.
7) Any other electrical sillyness.
8) Uneven front tyre wear and curbed wheels. Front suspension lasts well but
doesnt like abuse from curbs.

Tim..