As technologies improve, so you would think does the speed of the car, but this does not tell the whole story.
Jordan joined the Formula One world in 1991 and since then the FIA have been looking for ways to keep the top speed under control. Engine size has been cut from 3.5 litres to 3.0 litres, we have had the introduction of the infamous grooved tyres and now, in 2001, there has been a reduction in the amount of downforce allowed. These measures, and many others, have ensured that the average speed of the pole-winning lap, over a season, is kept in the region of 210kph.

The fastest lap ever was by Keke Rosberg in a Honda powered Williams while qualifying for the 1985 British Grand Prix. He completed a lap of Silverstone in an average speed of 258.983kph. Despite the newer cars being substantially more advanced, they haven't a hope of getting anywhere near this speed.

One way to judge the speed of the various Jordans - from the J191 through to the EJ11 - is to compare the top qualifying time by a Jordan against the pole time. This allows for the various technical limitations the FIA have put in place over the years and should give a good indication as to how fast a car was in a particular year, by comparing the car directly against its peers.

Interestingly enough, the well documented reliability issues aside, the EJ10 was actually faster than the J199 despite only scoring 17 points to 61, and no wins to the two in the 1999 season.
The EJ11, while over 0.5 sec. off pole in every race so far, is even faster, but the season is still young.

Generally, it would seem that Jordan is going in the right direction. As the team grows and gains more resource, they are moving closer to the pole time. The Honda works engine and the new facilities currently being built at Silverstone should definitely help the push to the front of the grid.