You're not a high mileage driver, it will take decades for the fuel consumption difference to buy the new car over the S-Max. Fuel economy and VED aside - the S-Max is the much better car - not even close. Better equipment, comfort, handling, ride, As the infamous South Park episode established - Prius drivers like the smell of their own f***s - that's the only plus point.

The S-Max sets the bar pretty high (or so people who have got one say. As a passenger, I wasn't blown away by it but then i'm prejudiced against MPVs)

but assuming you could afford to do it - would you?

No, because I can't think of anything that the pruis+ would do that the S-Max wouldn't. And that would always be my criterion when changing a car: What does the new car do that the existing one doesn't? It doesn't have to be a fiscal or technical reason.

No i wouldn't do it, and thats from someone who finds the S Max one of the most vile looking cars on the road, no offense beauty is in the eye etc..;)

What i would do though is treat the car to a birthday, assuming its not due for service yet i'd run it through the winter then when spring arrives i'd get it underbody steam cleaned then thoroughly serviced, bringing forward things like transmission and brake fluid change and full brake strip clean lubricate and new parts as needed, then let a good bodychap have it to touch up the chips and dings, and finally a thorough professional valet and polish. I expect the car to feel like new again once that little lot is done, a well spent £500 IMO.

I've often thought about a Prius, and if I just drove around town I might have had one by now. But as soon as you want to accelerate on the open road the CVT causes the revs to shoot up with a lot of accompanying noise.

So it depends on how much open road driving you do - and if I remember right, Happy Pink (nee Espadrille?) will have an opinion on the subject.

We often suggest an S-Max to people on here asking for advice on car buying - largely because there isn't anything else with that sort of capacity which is good to drive.

So maybe keep it unless you can get a good deal on another nearly-new S-Max.