Well, I have very little personal experience of the post 2011 312 model. Our present one is a 2010 169 model without the VVT valve gear.
We've had several of them and a couple of the older 141 models, the first of which actually had the old over head valve 750cc engine - That was the car my daughter learned to drive in and saw her through her time at Uni. It was replaced with another 999cc version which was my introduction to the FIRE engine. (I like the FIRE engine a lot!) Here's a photo of our Becky - 169 model with the 60hp non VVT FIRE engine. FIRE standing for Fully Integrated Roboticised Engine. I believe it was the first engine produced entirely by robotic machinery without any human intervention:
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I like the simplicity of the older models and the relatively "torquey" non VVT 1.2 engine they use. This means they pull well from low revs so are good in town. The VVT (Variable Valve Timing) engine, which was used from 2011 onwards, being used briefly in the last of the 169 and then carrying on in the 312 is criticised for having less pulling power at lower revs but pulls better at higher revs, so I would guess may be better as a motorway car and may have a little more "pep" for overtaking? They, the 169 models, also have very little in the way of "unnecessary" electronics. There are also some repair operations which are simpler - for instance doing front suspension arms when the rubber bushes eventually wear out (I keep our cars for a long time) is simpler on the older model, needing less parts to be dismantled to do the job. The problem for us up here in Scotland, is that rust is much more of a problem than it is for you guys down south, largely due to the copious quantities of salt used on our roads in winter. So finding an older car which is serviceable is a bit of a task. I'm always amazed at the excellent condition of some of the older cars I see when we are down in Devon visiting Mrs J's sister. She herself runs an old Vauxhall Agila which looks almost new underneath! I'm quite tempted to try to source my next car down there and bring it back with us next time we're there! I'd take another 169 without hesitation if it was pretty rust free!
You may have noticed "Felicity" in my Avatar picture. That was the car my youngest boy learned to drive in and was a special edition "Parade" with fabric sun roofs front and rear. By then my daughter was on her second Panda! After having passed his test he had a "coming together" in it which rendered it undriveable, so we helped him buy a Ford Orion - which he thought had much more "street cred" - She (Felicity) was already into middle age by then but I just couldn't bring myself to scrap her so I bought a set of cheap panel beating hammers and dollies and spent a silly amount of time teaching myself how to panel beat. I was very proud of the fact I didn't buy any new panels and managed to repair and spray it to a good enough standard that no-one spotted it had been repaired. We had that car for about 19 years until it got so rusty there wasn't any good metal left to weld good bits onto! It was a very sad day when eventually she had to go.
Hope that's of some help? Do ask away if you think I may be able to answer anything else.
Edit. Just to avoid confusion, the red Ibiza behind Becky is "Twinkle". The picture was taken a while back before I traded her in against the Scala (Bluey) which is now our "good" car.