Thats the problem mate, its very common.

A jammed thermostat, wrong housing etc could well be the cause of all the economy and running problems.

All the other things you list apart from the brake pipes and alternator I'd regard as "comsumables", although I've never actually needed a new clutch.

converted thermostat housing today temp sensor working again cost 2 pound and 60 miles of petrol at 15 mpg ver happy with my new modifide thermostat housing im going to post new thred on how to make the new housing that takes normal thermostat witch costs about 6 pound not 38 pound from the dealer the plastik ones dont last long

If your thermostat is stuffed and system is overcooling then this would account for your poor MPG if your car is an MPI version as the temp sensor doubles up as a fuel temp sensor.

My thermostat isn't working (jammed open), the engine is running very cool (temp gauge doesn't move off the stop unless engine left idling whilst stationary) but mpg is still good. Mine is a 1999 Felicia 1.3L MPi - (Siemens). Maybe the Mono-jet system does things differently I'm going to change the thermostat ASAP anyway.

Tim

converted thermostat housing today temp sensor working again cost 2 pound and 60 miles of petrol at 15 mpg ver happy with my new modifide thermostat housing im going to post new thred on how to make the new housing that takes normal thermostat witch costs about 6 pound not 38 pound from the dealer the plastik ones dont last long

Hi snottie, i'd be interested to learn about your modified housing.