Class G is the cheapest that will allow you to earn full miles.

I suggest booking with a travel agent in Delhi (there's tons of them), and tell them EXACTLY what you want: Lufthansa DEL-FRA-PHL-FRA-DEL in class G

To find out what the price should be, you should go to http://matrix1.itasoftware.com.

In the "to" box, type:
PHL::+/f bc=g
In the "from" box, type:
JFK::+/f bc=g


Then fill out your dates and stuff. Booking city should be DEL.

It will tell you exactly how much the ticket should cost, so that you can make sure that the travel agent is charging a fair price.

Hope this helps...

If G fare availability is there, and you find a travel agent who can book it for you, then book right away. Just make sure that the ticket is in G class before paying (travel agents often will try to sell you a cheaper ticket and pocket the fare difference).


Edit: bad news, Lufthansa has changed their accrual rates (new rates displayed here: http://en.aegeanair.com/milesandbonu...les/#LUFTHANSA), so V class no longer earns 100% miles. The lowest class is now G. I'd seriously give US Airways a look...