The pre-1950 issues have some value as once wartime paper rationing was introduced print runs were slashed and most magazines could only be supplied to a newsagent on firm order - sale or return essentially disappeared in the news trade and newsagents necessarily cut their orders to what they knew they could sell. In practice, this meant that only customers who placed a firm order were guaranteed their copy (always assuming the newsagent could actually get as many as he wanted - not always the case). And even then, a lot of the ones supplied went for salvage afterwards. So the wartime ones especially are rare. Paper quality is usually poor as well - although the 'war economy standard' paper used for books has proved surprisingly durable as it was acid-free, unlike later cheap papers used for paperbacks in the 1950s and 1960s, which are brittle. The acid also attacks and dries out the glue used in so-called 'perfect bindings', which is why old paperbacks just fall apart!
Quite a number of magazines simply closed in 1939/40/41, some were amalgamated in order to preserve the paper allocation and others changed publication frequency and/or format: Light Car for example, which went from a standard format weekly to monthly in 'digest' format.
The print runs of Motor Sport in the 1960s were enormous, so those are by no means rare or valuable unless in bound volumes - ideally Motor Sport's custom black hardback bindings.
Frankly, the post-1950 ones are essentially worthless unless bound - at least this side of the Pond - but decent individual copies of the pre-1950 ones can command anywhere between £5 and £20 each.
