Buying a used BMW! HELP!!!???

A good friend has 12-18g's to spend on a car. I'm trying to talk him into buying a used BMW. He's worried about gas mileage. Personally I'd love to have a 6 or an 8 BMW, but my 4 will do for now. Can anyone suggest a good model BMW that would be economical and would be a good buy for 12-18g's? Trying to sell him on the 740 but he's worried about gas prices... HELP!?!?!?
Thanks.
Love my BMW!

BMWs get poor gas mileage, but they make great power.
My '05 325i is getting about 16 mpg with about 1,100 miles on the odometer.

Not on the highway

My 328ci gets awesome gas mileage on the highway. I drove from Kentucky to Georgia on one tank and I took the long way thru Tenn., N. Carolina, and S. Carolina.

In the city gas mileage sux but if u can keep your foot out of it you will do Ok.

The last 4 cylinder BMW with a back seat imported to the U.S. was the 1998 318i. I have one that gets low 20's in town and around 30 on the highway. It's silver, automatic, Touring alloys, etc., 75,000 miles and can be yours for $13,000.

for $5500 i you can find a 93 535i 5 speed manual, then the extra money dump into performance parts, the bigger the engine the more gas it will consum, so try not to push him into a 740