Mike. There are some hard-ridden K12's about, Martin (fjtwelve) just passed 70 odd thousand on his K12S which was a pig when I rode it and compared it to my K12S. He spent money on a remap and it is still going strong.
The 12 has dire fuelling, the early ones (mine was a 2004 press fleet bike) were unrideable. Later ones had a new airbox and idle control valve (£500 to do it now) and an ECU update which sort of fixed it...
The 12's early electric servo brakes were awesome, but with no feel; pull the lever and it was like hitting a truck! They suffered from brush failure and were difficult to repair. Even the later 13's are not without their difficulties in regard to ABS.
The 12 as well as early 13's suffered from cam chain rattle on start up caused by a flawed tensioner design. Hot starts (especially after standing on the sidestand) could result in the chain jumping the crank sprocket which allowed the pistons to say 'Hello!' (followed immediately by 'Goodbye!') to the valves...a new tensioner with an oil reservoir and a plastic doohicky round the crank sprocket solved that one.
12's were prone to rear shock linkage failure which tends to test out the worthiness or otherwise of all your safety-related clothing...
A 12 is just as fast as a 13, maybe faster by 1-2 mph and in the real world there is little difference in engine performance.
As I said, the fuelling on the 12was a nightmare. Ricardo Engineering sorted the head with a new design for the 13 and the fuelling is more or less spot on; I still don't think it is a patch on the seamless fuelling on my old 1987 Honda 1000!
The chassis is a totally different matter, the 13 has one, the 12 has a rather thick plank of wood! You can choose which side of the white line you want to put the contact patch on a 13, on a hard-ridden 12 you are lucky if you can choose which side of the white line you put the bike...
The 13 has much better ESA with greater differentiation between the various settings.
The 12 suffered from sticking throttles - no adjustment, no cure apart from new throttle bodies - £1,000 to you sir...
Lots of 12 owners can't understand the attraction of a relatively more expensive 13. No 13 owner that I have ever met would go back to a 12...
The 12 was better in some ways. It didn't suffer from switch failure. OK, the 12 was better in one way...
Go here...
http://eurokclub.bike/index.php?topic=2648.msg32379#msg32379...and read the list of things replaced on Steve's K12. He is now a salesman for BMW Motorrad but look at what has gone wrong down the years.
You are way out of line in your thinking about BMW bikes as compared to cars, not that I have ever owned a BM car.
I can list on the inside of a gnat's ear lid the top notch components they used in their bikes. It would take an hour to write the list of rubbish components and designs...
Front end Ball Joints - made of cheese...
Switchgear - cheap as chips and last about as long...
Radiator spray guard - covers the bit of the rad that never gets dirty...
Front mudguard - covers the bit of the rad covered by the rad spray guard, chucks tons of rubbish at the unprotected lower corners of the rad which clogs causing overheating and rotting of the alloy core...
Clutch design - done by a seven year old; rone to running dry, wearing, squealing and juddering...
Side stand - too short to stand the bike on for most people's liking...
Cheap rivnuts in the frame which come loose and can strip especially when the bolts have the specially made BMW loctite (read Araldite) applied...
Engine vibrations - another 7 year old, especially bad at motorway/Autobahn cruising speed assuming you stick to the limits...
Paint finish - bubbles and peels on rear swing arm/final drive unit and clutch/engine but also wheel carrier (forks to you and me)...
Fuel level sensor - buy a notched stick and keep it taped to the tank...
Headlamp unit - only a four year old would design something where you can only adjust both at once and for me, neither is in the right place on the road...
Hot-starts - lots of bikes suffer from an inability to start when hot; a new section of loom resolved that one but it is expensive...
Battery - life for some bikes is abysmal...
Fuel tank - take off made of plastic which fails, a recall for that one...
Dealers - some good, some less so; the best one I found was in Athens...
Front ESA unit - loom prone to failing; they sell a repair kit which most dealers have never heard of...
Some 'sealed-for-life' things like the rear drive and the clutch hydraulics shouldn't be...
However, it is, to my mind and most in here (who of course are all biased and bonkers) the best bang for your buck sports tourer ever made. Discuss...
Simples!