Tim, i've seen that Bahama Sprint in person and spoke to the sales guy, they know it's a S4-Sprint and even tried to tell me that made it more special (probably to justify it's huge price). It's been very nicely finished.
Mike, Yes the cam cover script facing forward is a dead give away, as far as i'm aware it's only the S4-Sprints that have the cam cover like that and they are very rare (make sure you have 'N' stamped into the head at the back of the spark plug channel), No engine number on the chassis plate (usually means it was supplied as a Kit which seems to be another shared feature of the S4-Sprint), Key on the Dash, early steering wheel (no thumb pads but not sure if some production line sprints had those too), No lip under the boot floor (you might also find the front exhaust back box mounting bracket holes missing as S4-Sprints had twin back boxes that didn't have the bracket), Lump in the bonnet, Originally silver wheels, rear section of the side decal fitted parallel to the bumper, two Championship badges rather than a one and a Sprint badge on the production line cars..... Also White button hand brake, i am not 100% sure thats an S4-Sprint only thing but i've not seen a Production line Sprint with one fitted (they usually have the twist lock type) same with lack of Sun visors (not 100% that was just the S4-Sprint)
A dead give away if you have a S4 that some one has made look like a sprint in it's past is the way the Black is painted on the back of the door (assuming it's not been fully stripped back to GRP) the S4-Sprints were masked the same as the production Sprint which is different to the S4....... Scary i know that
Another interesting one i noticed on my car was the Dash loom had been cut in the passenger foot well and two period (grotty) white multi plugs fitted, as my car was one owner i asked about it and he couldn't remember any electrical work being carried out on the car, plus there was no receipt (which is odd as he kept everything).... i didn't think anything of it until i saw my +2s (that the original owner had got quite heated in correspondence with Lotus about it being a +2s that had been retro fitted to +2 130s spec) had the exact same plugs, so i guess Lotus took the dash out for some reason after the car was assembled/wired up during the retro fit process.
As for dash, the S4-Sprints were basically just Retrofitted S4 se's so the dash is identical to the S4.
Sorry not the best picture but you can just see the key ring behind the steering wheel.
Excuse the oil leak, not very flat Cam cover + cometic gasket = puddle on floor
I much prefer the silver wheel myself, the Black ones with the chrome trim make the rims look an inch or so smaller from a distance (bit odd imho)