This might help you work out what you want/need.
https://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html
I have a Td5 90 with 235/85/16 tyres and a disco transfer box and I can sit all day at 65, I've never owned a car so I am well used to using a series on a motorway so this 90 is refined by comparison.
I have a 200tdi in mine, ignore
@lynall saying to forget one of those, that are fine, and much easier to work on than the later models. Also ignore any one telling to buy a rusty discovery, they will just be trying to off load their one so they can get a defender instead
Mine is a 200tdi, 1.2 transfer box, 265/75/16 bfg AT's and I get 50mph at 2000rpm and 75mph at 3000rpm, but similar to
@wireman I tend to stick around 65-70. I do about 25k a year on mine (including towing) and it is fine on the motorway. I have some sound proofing on the bulkhead and seatbox, and a full headlining, but other than that is is a standard hardtop. I did 1000 miles of solid motorway driving in 20 hours earlier this year on the way down to morocco, and got out at the end of the day feeling fine. MPG is the problem, at 65ish I can get 27mpg (I run heavy with addons and have a roof rack) but if I am doing a run at 75-80 that will drop down to 23/24mpg.
I am in same boat as
@wireman however, I bought the 110 when I was 18 and have it is all I have drive meaningfully for the last 10 year other than the series so I am very much used to its speed, comfort, and mpg levels. Due to this when I have toyed with additional vehicles (jag s-type, work Hilux) although they will go faster and possibly be more comfortable (a debatable point as I am so used to the 110 I adjust every other car seat to be as near to the 110 driving position as possible) for me this did not out weigh the down sides, such as sitting on the floor with no visibility of what was going on around you, and being full of electrical gimmicks I did not want and just went wrong!
