What about a Lexus GS 300 
Cheapest Lexus automatic on Autotrader within 40 miles of here is £5k. Manual £2k - more than I want to pay. It's an IS200 a which means absolutely nothing to me, but it doesn't look very big.
IS200 is small imo 
Very and no head room.....also not nearly as relaible and well made as you would hope.
It's not often I disagree with the Master.... Although having met old long body/short legs, I have to say I have less head room issues in the Lexus than the omega elite with a sunroof. Both have electric seats which tend to sit higher due to the motors underneath and a sunroof which takes an inch of head room as well.
And while the is300 has its faults, there are far less faults than on an omega. FAR less. Me thinks Master has his Vauxhall tinted spectacles on again.

Not at all, I help maintain a 2.0 Auto one and its had an auto box, cam chain, pretty much every suspension bush plus the usual consumables and it lunched a cat.
And headroom wise, there awful, no where near as much as pretty much every other car out there, as bad as the old rover 200's
Head room exactly the same as an omega Elite, little legs.

not as wide as omega inside obviously, but being 6ft1" I dont have a problem driving it at all.
Mates Mrs has 150 k on her 3.0, and over and above consumable service items, its had a lambda sensor, that's it! ...and it drives tight as a drum. If only omegas where that reliable.
I wouldn't give the 2.0 a second glance anyway though. (Weaze)