The 1998 was manufacturing worst year for Volvo's S70 and V70. Lots and lots of maintenance and reliability problems. They solved most of the problems the next year, and the Model 2000 was a great year.
Power and Performance Volvo S70:
100 amp alternator
520 amp battery
Axle Ratio: 2.80 axle ratio
Fuel Tank: 18.5 gal. fuel tank
Download Volvo S70 service manual for owners with pdf format here. Most unreliable car ever, this thing is in the shop constantly and has been nothing but trouble. It breaks down all the time and I do not recommend this car at all.