Vti Civic 2004-2005 : you should be able to get a low mileage one in about 1Million.
Fuel Economy : 12 kilometers per liter in city. Up to 15 kilometers if a manual driven sensibly.
CNG Consumption : 120-140km per cylinder in city. 180-190km on highway at 100-110kmph.
Parts availability : Absolutely easy.
Maintenance Costs : Not high. Higher than an xli maybe, but the difference would be minor.
Reliability : Great amongst desi cars.
Braking : One of the best amongst local cars.
Road Grip : One of the best amongst local cars.
Speed : Goes up to 200kmph, maybe a tad more too. 0-100 in about 9 seconds. Pretty good.
In short its a lovely car to keep. If you'll be traveling a lot, you would rather have a reliable and safe car, economy comes later. Despite life and death being a matter of fate, good braking and road grip keeps your mind at peace.
Just make sure you get an absolutely awesome car..since you have money, buy the best one there is in the market. Be patient, and don't hurry in your search.
P.S. PM Killervtec - he has an awesome VTi Oriel...one of the best ones I know of. I'm not very sure if he's willing to sell it or not.