Some would consider the idea that people can derive enjoyment out of spending hours tinkering with spring, damper and suspension settings the first signs of mental illness, but we like nothing more than tweaking gear ratios, adjusting brake balances and getting our toe-in and camber angles just right. So when we heard that the latest addition to Simbin's racing stable included not only a whole host of new cars, but a faithful recreation of the legendary Nordschleife at the Nurburgring, we were practically drooling Castrol Magnatec in anticipation.

GTR Evolution is an add-on pack for Race '07, SimBin's World Touring Car Championship (WTCC) simulation. It builds on the original title by adding souped-up versions of the WTCC cars for a new arcade racing mode, plus a selection of supercars, including the super-sleek Audi R8 and the monstrous 806bhp Koenigsegg CCX. The most notable additions in the expansion, however, are the new tracks. Three variants of the Nurburgring circuit have been added to the already hefty track roster. The shortest of these is the modern Grand Prix circuit, which is the current host of the European Grand Prix. At just over three miles long, it's a pale shadow of the much more famous Nordschleife (Northern Loop), which, at just a shade under thirteen miles long, is an immense test of driving skill.

Sir Jackie Stewart famously dubbed the Nurburgring Nordschleife circuit "The Green Hell" when it was still a Grand Prix track in the late 1960s. When driving this wonderful virtual recreation of the circuit today, it's easy to see why. The challenge doesn't just come from the extreme length, but also the variety of turns: low speed, high speed, off-camber, over blind crests and even turns with banking, the Nordschleife has it all. Exhilarating and terrifying at the same time, hardened petrolheads the world over consider it to be the ultimate race track. Though if that's not enough of a challenge for you, also included is a hybrid of the Grand Prix and Nordschleife circuits - the fifteen mile endurance layout. This track, however, suffers a little from the combination of the old and new Grand Prix circuits and doesn't quite have the same character as the Nordschleife and so is a little less fun to drive.

It may seem like a contradiction in terms that The Green Hell could possibly be fun to drive, but this is testament to the excellent standard of the modelling within the game. The driving physics are second to none - as you will find out the first time you roll your car onto its roof, after misjudging the entry to the banked Karussell corner, or have the Koenigsegg take off at thirty degrees over the bumps at the appropriately named Flugplatz. The physics are also brilliantly showcased during wet races, where corners that were merely horrifying in the dry become utterly petrifying. The lack of grip sucks away any confidence you have in the handling of the car, making lap times skyrocket. You can compensate somewhat for the lack of traction with different lines around the corners, but (wet or dry) it's through altering the mechanical settings of the car that you can gain the most advantage over your rivals. The sheer depth of the car setups (while unchanged from the rest of the Race series) give the player so much control over how they can get the individual cars to handle.

The sonic feedback is also excellent, with the EAX-enabled positional audio giving you the subtle cues you need to determine when the car is bottoming out over bumps and sense which end of the car is sliding during understeer or oversteer. This makes adjusting the brake balance on the fly while you are on the circuit much easier, and also helps in the task of altering suspension and anti-roll bar settings when you go back to the pits. Though should you not want to spend hours and hours driving under the bonnet making the smallest of incremental adjustments to the setup of the car (we can't think why), you can let other people do the hard work for you and simply download setup files from other players that have been shared online, with an integrated voting system allowing you to determine which setups are the most worthy of download and will likely yield the best improvements to your lap times.

If there's one area where GTR Evolution doesn't impress however, it's graphically. It's hard to see any tangible improvements over the previous entries in the Race series, though at least this does mean that the frame rates remain nice and high. The tracks and the cars still look good, but the texture quality could certainly be improved and are not up to the standard you would expect from a current generation console title or cutting edge PC game. Worse, the Steam version we played with had a very annoying habit of minimising the application at random intervals (usually at the most inopportune moment during a hot lap) and during races on the Nordschleife the 3D engine occasionally had problems that resulted in corrupted textures and rendering freezes. Hopefully these issues will be fixed in subsequent patches, but it's a little disappointing that they were not resolved before release.

It's not a stunner visually, but there's still an incredible amount of detail in the tracks.

Though disruptive and annoying, the graphical glitches do not have such a large impact on the game experience and are more than compensated for by the other aspects of the game. In terms of actual racing, the AI remains aggressively competent, making few mistakes and will shame most casual players at 100% skill, especially in the wet. Truly committed players, however, will get most mileage out of the game online, and the slick server browser makes finding a race as easy as a couple of clicks. The game also gives you quick access to SimBin's web portal that catalogues all the community sites for the Race series, should you want to get seriously involved in the online racing scene and participate in full championship seasons with the real hardcore.

GTR Evolution is definitely an evolution of the series, as opposed to a revolution, and while the game is in need of a graphical overhaul, the rest of the game is all you could ask from a racing simulation. Not only is the AI strong, there is a lot of community support (not only in terms of online races, but mods and setup files as well), but the handling model is flexible enough to allow easy access for more casually inclined players while being realistic enough for the dedicated simulation audience to make use of the slightest setup tweak. It also has a wide enough selection of tracks and cars to appeal to a mass audience and is fun whether you decide to race in anger or simply drive for the sheer enjoyment of it. The Nordschleife circuit is the crown jewel of the game (and the Race series) and justifies a purchase regardless of the graphical issues. Some may call it The Green Hell, but we prefer to call it Tarmac Heaven.