I have never seen this car before.
It's one of the Mark 3 Scalextric types which is the same as the kit Hornby released and also the same as the plain white cars that Rob Smith and myself secured/sold.
Looking at the decals - they are just that decals - the DHL on the bonnett is the give away red on clear applied over various panel lines - so not tampo printed.
The kits are a great bases for a re-paint job;
Plain white car (not a kit) made by Hornby. (limited edition of 500).
Plain white kit - painted and decal by me.
Plain white car (not a kit) made by Hornby (limited edition of 500) bought from me by the Dutch club and then tampo printed - Limited edition of 110 (from the 500).
My guess is that it's either an after market re-paint or a test idea made around the same time as the DHL series made for Spain by Hornby.
link to DHL collection
If it's a DHL test mock up made by Hornby - then probably the only person who can verify this will be Adrian Norman.
Where did you get it from?
The passenger seat is missing - this may help determin if it's from the kit or the white cars.