Hi Daniel,
Welcome along.
To try and answer your questions.
1. Can't answer that, really have no idea about your circumstances but the 260 is much more fun to drive.
2. Lot of members use their 260's as a daily driver. Average 22/23 m.p.g.
3. No ISOfix, I transport my grandchildren in my 260 using standard child seats but don't know the laws in your country.
4. 22K is a lot of money but the 260's fetch high prices in Europe. Cost of UK model approximately 8K.
5. Clutch replacement anything up to 80K miles. Some go sooner, depends on how its been driven.
6. Parts availablity is OK. A few hard to source bits but the club have re-manufactured brake backplates, brake discs, shock absorbers etc. Most things are solvable. Oil and filter every 5000 miles, everything else normal intervals.
I am afraid I can't talk you out of the car, I've had mine for 14 years and still love driving it.
Hope this helps.
Nich.
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