Capri 2.8i fresh out of the factory would have been 160 bhp. Fuel consumption will be around 30.1 mpg motorway driving dropping down to around 18.7 mpg urban driving.
Value is obviously dependant on condition prices vary from £500 to £800 for a project car up to silly money for a 280.
Parts although still available are becoming more expensive. If you do opt for the Capri consider joining Capri Club International (CCI) always good for sourcing spares. Also check out CapriPowerForum for advice.