I changed my Mondeo ST to a Focus ST. I was surprised how comfy the ride is compared to the Mondeo - not as comfy, but still very good that you can do long trips without back ache etc..

I did 20,000 miles last year in mine and I'm still averaging over 30mpg. I do 75 miles a day on busy roads so keep it at about 60>70mph so can be economical if you drive it leisurely.

I do have more "exhilarating" moments though but it's stayed over 30mpg somehow. Bluefin stg2 + Airtec Gen2 intercooler. No other performance mods.

Things to check:
Alternators - especially 06 platers
Oil Diaphragm replaced yet? If it whistles a bit, then pull the dipstick to stop = needs replacing
Front lower bushes replaced with powerflex stiffen things up nicely at the front.

They're generally pretty reliable if well looked after - walk away if there's not a good service history.