The contents change from time to time but last November went I went through it looked quite full.
The military stuff is actually quite interesting and well presented. About a hall and a half last time I was there. It seems to have taken over some of the space that was previously occupied by largely non-racing exhibits..
As VIVA GT said some of the loan exhibits move around from time to time as do some of the Wheatcroft collection cars which are loaned out. There are no doubt some exhibits (not just cars and bikes) that are away for work to be done leaving apparent spaces in the displays.
I suspect that rumours of the sale of a few cars over the years are likely true. I think a few have found their way back onto tracks on a regular basis which may not be so bad for their reputation and the interested public. Most significant British and Commonwealth cars of the period still seems to be well represented. Of the GP cars I suppose getting a full complement of German and Italian machinery might be a challenge ...
Last November there was a rather interesting display of Jaguar prototype and design study cars on view. The early aluminium era. Loaned by Jaguar apparently.
The McLaren collection included shapes from up to about 2010 or 2011 iirc. Whether these modern cars are real or promo mockups without most under-the-skin components may be a matter for debate of course. Interesting to see the aero differences side by side though.
I think it was back in the Gillet days but at one point there was a software outfit that produced some sort of interactive web site for the Museum. From memory I thought at the time that it looked quite interesting. I have no idea what happened to that ... but one might guess it went AWOL.
It's not hugely expensive to get in and I have always felt that, in context and for racing enthusiasts, it offers value for money. I've been fortunate that for the past 3 or 4 years the Donington Park Racing Association Club's AGM has been in the Senna Suite in the museum complex and one has to suffer the challenge of walking all the way through the Museum to reach the Suite.
The link from the Donington web site may be useful if you have not already seen it.
http://www.donington-park.co.uk/abou...ix-collection/