Why should mileage be a problem?
i've had my car 2 months now and do 35,000+ a year. I got the car converted to LPG (which will pay for itself in 6 months which is handy when greenfuel gave me 6 months %free) and my fuel cost so far has probably been less than it was with my cdti previously!
OK I stil need to fill it up twice as much, but if you're doing a lot of driving i think it makes sense to have a "drivers car"!