When it comes to registration details and buses i wouldnt pay much attention to it. My Dennis Dart registered with an engine size of 0cc on the logbook which I had to get changed to apply for a cheaper (non PSV) tax class because they require the engine size to determine the rate.
I usually see the actual engine size like 5900cc/5883cc
(well, at least "actual" until the Dart switched to the ISB3.9 in October 2001 but earlier such examples were still down as 5883cc as if they forgot to change it, similar to when Optare's 6-cylinder Cummins engine option changed to 6700cc in 2007 but they kept being registered as 5900cc for a bit), but I do see the odd 0cc. This is the first time though I've seen complete nonsense like 2000cc for a Dart.
What Dart do you own?
Also when it comes to registration a lot of them have the body down as make/model eg Northern Counties Palatine rather than Volvo Olympian, I get the impression a lot of it was done on a "dont really care" basis!
Interesting - pretty much all the "different chassis and body manufacturers" buses I've put in the DVLA checker have come back as the chassis manufacturer as the make. I did though once see an oddball coach that had one of those "manually entered" makes, and it was e.g.
PLAXTON PROFILE rather than e.g. Volvo or Dennis. As for the model field, I've only looked at that (obviously on some other service) for integral buses, specifcally Enviro200s - they were blank, so were registered merely as an
ALEXANDER DENNIS (or even
ALEXANDERDENNIS without the space) "no model".
Im pretty sure when it comes to registration dates theres an odd case of a Dart SLF with the original Plaxton Pointer SLF bodywork which is registered on an (i think) 56 plate? Cant remember details but it was a demo test bed or something and wasnt registered for the road until 2006/2007.
Yes 56 reg (MC56 HAM). Specifically a Pointer 1-bodied SPD, and mentioned as early as page 1 (and 2). November 2006-registered (with "Alexander Dennis" as the make!) although actually currently on SORN. One of just two built. The other one (non-late-registered, "Dennis" September 1998 S-reg S861 VAT) "disappeared" according to
@stadler, but is actually showing up on the DVLA checker, albeit also on SORN.