Yes. Or, as I said:
A lurcher is a cross or mix of sighthound plus another type or types of dog.
So, a lurcher bred with a gsd (or mix) will still produce lurchers, just with a lower percentage of sighthound blood. The description of a 6ft jump from a standing start is very lurchery!
You will meet people who say the only 'true' lurcher is a greyhound to collie cross (bearded or border) and they probably were vaguely that originally when they were required not only to hunt but to herd. The type has been expanded and extended though down the centuries depending on need and fashion.
I know folk who can describe their lurcher's genetic makeup in fractions all the way up to 64ths including all the ancestors' names and others who, when asked about their dog's breeding, will just say 'Oh, lurcher to lurcher'.
Greyhound/whippet crosses in various degrees are very popular for the country show lurcher racing/lure coursing circuit (longdogs also count as lurchers) although there has been bit of complaining in the past about dogs of 15/16ths greyhound - 1/16th whippet competing. In the opposite direction 'non-ped whippets' which are mostly whippet with a smidgen of greyhound have their own competition scene.
A while back a character (Greengrass, was it?) in the tv series 'Heartbeat' had a lurcher and suddenly all lurchers had to look like his - grey and a bit shaggy. Now the televising of flyball from Crufts showing incredibly fast teams of lurchers, whippets and 'border whippets' is bringing that smooth-coated 'racy' type into higher popularity.
My current dog has six breeds in him; three different sighthounds, two different gundogs and a herding dog (not necessarily in that order). Is he a mongrel? Yup. Is he a mutt? Yup. 'Lurcher' is just the term used to describe dogs bred like him, originally to do a particular job, which share certain characteristics.