Of those three I'd go for the Accord. I don't think the Lexus is worth the extra cost, particularly with its higher mileage; and avoid Mazda diesels like the plague. There are well-documented serious problems with this engine.

Is your annual mileage with this car going to be over about 15,000 a year? If not, consider a petrol-engined car which will usually be cheaper than the equivalent diesel.

If it were me I'd add the Ford Mondeo, Skoda Octavia and Volvo S60 / V50 to the list.

Why diesel ? Many posts suggest only if you clock up at least 15/20k annual mileage. Mainly I gather for sound technical reasons related to modern diesel engines such as those in your listed options.

A quick look at autotrader suggests a 2.0 petrol accord for the same sort of budget could be a year or so newer, and quite a lot lower mileage. Yet they will still do 40 on a run, and are about as reliable as cars come. for your use, and stated budget, thats what i would go for.

Lexus... it's the Japanese Mercedes!

Wouldn't touch the Mazda with a barge pole - well known DPF regen probs resulting in engine failure. The Honda is okay in most areas, The Lexus looks nice and has a nice interior, but the Toyota Avensis with the stunning T180 diesel engine is a better motorway car. Bang for your buck you'd be best off with a top-of-the range Mondeo.

I'd have a look at a Mwecedes C class, there is a good choice about and you don't have a cam belt to worry about. out of your 3 the Mazda looks interesting.