I get similar figures to 'Hotblack', 'TrentL' & 'MattMarky' in my Calais. I do a lot of country driving and avg 9.4 L/100Kms. My best has been 8.7L/100Kms. (driving like a old fart). City driving increases my fuel consumption to anything between 10 and 12 L/100Kms.
The only way to test them (your injectors) is to remove them and test them on a proper test bench. Just buy some change-over ones.