The EU are going to pick their battles, if they consider we are breaking rules. Us buying a few diesel engines from a German factory to fit on bi-mode trains will be way down the pecking order when compared with other trade issues concerning N Ireland, fishing, financial services etc
The issue with buying from the EU will be that they'll stop making the engines that don't adhere to their own standards. I suspect the EU would be fine with us giving exemptions for engines coming into the UK. The difficulty would be if say Rolls-Royce or Caterpillar wanted to export engines that met UK standards but didn't meet EU standards.
I'd be staggered is other countries don't break EU rules all the time around the edges
They do, but usually would get exemptions to do so rather than start rubbing people up the wrong way. It's also remarkable just how much products you think of as the same change around the world to meet different standards. Also the member countries front and centre of the EU break their rules all the time!
Close alignment surely only relates to exports to EU and imports from EU countries. Once stuff is here and assuming it isn't going back to EU later then we can do what we like. The EU are not GOD, they make rules, many of which we will be happy to agree with as they are based on science etc
This is all true and good points. However, if we only import and cannot export it isn't going to help the economy in the long term.
We probably had some input in the past, but some EU countries (particularly Germany and France) have an agenda which sometimes surfaces. Germany makes sure rules relating to EU vehicles comply with their motor industry's wishes to the detriment of climate change. EU rules don't seem to stop extremely polluting Brown coal being burned at a prodigious rate in Germany either.
We had a lot of input in the past, as the 2nd largest economy in the Bloc. All member countries have an agenda, all the time. It just depends who's agenda wins out at each meeting (or which trade-offs are made to get other points of the agenda through). Germany, France and the UK, as markedly bigger economies than the rest, tended to get their own way quite a lot of the time. As examples, Germany got the motor industry, France got the CAP and the UK got the Finance industry.