I'm a bit confused about speed limits for vans - on the Autopista/Autovia it looks like no matter the weight of the van (like a Citroen Jumpy/Peugoet Expert/Opel Vivaro size less than 3.5t) they are lumped in with trucks and restricted to 90km/h even though they weight less than the normal 3.5t cut off - whereas campers/motorhomes are allowed to do car speeds (120km/h) unless they are over 3.5t where they are then restricted to 90km/h.
Is that right?

Based on nothing other than the chart you have provided, it looks to me like a lightweight van which has passenger- carrying variants, including the vehicles you mentioned, would fall under "Vehiculo Mixto Adaptable", and therefore allowed to do 100kph on an autopista.

If you choose to register your vehicle as a "mixed" category, you make considerable tax benefits on the purchase price. The penalty is being treated as a commercial vehicle and taking the speed restrictions that apply.

Yes, I can see the mixed category and that makes me wonder then if the vehicles I mentioned are classed as adaptable. I'll have to look into exactly what they mean by that, e.g. a van version and I suppose a passenger version.
It would be a second hand vehicle already registered in a different EU country but I note what you say about the tax thing.
I've just started looking into the speed aspect so I don't start clocking up fines for the EU countries I'd regularly travel in and Spain seems to be the exception in that the others allow car speeds for a van bigger than a Citroen Berlingo type but less than 3,500kg.
Thanks.

Be very careful about having the vehicle registered as mixed or adaptable as they will require an ITV every six months once ten years old.
I have a Mini Moke that was registered from new in 1988 as mixto as it states 2/4 seats, if you have a passenger version of a Ford transit connect and the seats are removable then it will be mixto and the above with the ITVwill apply.
Also be very careful about the classification of the vehicle in its home country, an idiot friend of mine buys his cars from Germany or Poland and he has been stung twice now as the cars were 'taxi's' and were registered as that in the originating country. Again ITV every six months.

Thanks for the info. It will be registered already as it will be second hand in a different EU country and won't be registered in Spain. It's quite difficult to miss a car being registered as a taxi I would have thought. It would say so on the registration document so I'm not sure how that could have happened unless not knowing about the ITV issue was the... err.... issue.
The slightly longer story is that the van would be driven to Spain, converted to a camper, driven back to its home country and then registered as such back there. That for me would then make the uncertainty of speed limits disappear whenever it is brought back again as that category is quite clear in the DGT graphic above.