A5 Sportback S Line TDIe

Hi,
looking to replace my company CC in September and thought I had settled on the rather dull BMW 5 Series Efficient Dynamics until I spotted on comcar.co.uk that the A5 Sportback in S Line trime with the 177 TDIe engine is on a par with the 5 in the 17% tax bracket.
However, the lease deals on the A5 sportback are not very good and will probably price it out of my range. There are lots of good deals on the A5 Coupe, but unfortunatly it doesn't seem to come in the S Line/TDIe combo, even on the Audi.co.uk configurator.

Just wondering if anyone could answer why this might be? Seems strange to offer it in one but not the other.
Cheers.