I've always fancied a Citroen DS. (If you could go older, a TA would be even better)
Or a Bond Bug.

If its a second car then sensibleness is less of an issue, when I had my MG it was my only car, it was perfectly reliable and practical in most senses (apart from being the coldest environment on earth for 8 months of the year) but the time spares took to arrive, even though they were really cheap, could make routine servicing and repairs an expensive burden sometimes.

I still don't see tax as being much of a burden, even at the current high levels its still an insignificantly small part of the cost of running a car, its just a lot to spring for in one go.

Though not quite 30 years old yet, a worthy replacement for the DS. I give you the Citroen XM estate.

http://katalog-automobilov.sk/img/citroen-xm-break-2-1-td-1.jpg

These are awesome estate cars with huge interiors and a brilliant ride. I bought one for £600 and drove it to the south of France twice. Did nearly 30k miles in it. It proved pretty reliable until the clutch cable snapped!.

Citroen DS

This is from a company based in oxford who are specialists.

my passion is however the mk1 escort.Love the minis in one way although in others I don't.Love the Dolomites too.Fiats are good too. Lancia anyone??MK1 and Mk2 golfs are pretty good too.

DS for a time were made in slough!

Aye Gordini wheels, one of the websites I frequent is building a 4 with a Gordini engine in it at the moment. Though as it will be all very discreet I think he's sticking with steel wheels to keep a sixties look to the car.

http://www.renault4.co.uk/renault-4-restoration.htm Mmmm tasty!!!

How come only one vote for a Land Rover ?
If you want something you can load up with bikes and kit then just get in and drive when you need it, and abandon in a field when you don't, it beats any of the exotic high maintenance cars mentioned so far.
Just look around at the 30 year old vehicles you see on the road.
Cars get pampered and kept in garages and only taken out on special occasions.
Land Rovers get thrashed around off road, overloaded and hooked up to heavy trailers and generally used like a working vehicle with no regard for their age.

I love Landy's, have spent years racing and competing in trials and off road competitions. We put Nissan Patrol running gear on them for strength and reliability. They are rubbish really but we love them, would never use one every day on the road, crap mpg, crap driving position and crap reliability, disco's are worse still. On the other side easy to fix and repair which is just as well, most of the back taken up with tools and spare parts. Great fun for an occasional blast on a weekend though.

Oooooooooo! So many lovely cars. That DS and the TA made my heart skip a beat. I had a Manta Mk1 for a while, beautiful car, loved it to bits. Those little Renault 4's are amazing practical cars, and can practically go anywhere.