Every possible option for addition into the 1998 GT1 category.
The category in-game is not named 1998 but I've restricted this post to 1998 because of the fact that the 911 GT1 is the 1998 model, significantly developed from the 1997 model of the previous year. And 1999 was the death of the official GT1 category, as these cars had turned into basically expensive prototypes, which means no new cars were homologated past this point that I know of. So 1998 it is.
The entries here will be taken from all of the races i could find running GT1 cars in this year, first with the obvious ones:
Toyota GT-ONE
By all accounts a prototype in all but name, this car entered in the GT1 category at the 24 Hours of Le mans in 1998, where one of the entries finished a respectable 9th. The other two however DNF'd along the way. It made a return in 1999 now in the GTP category where one car finished 2nd, but two of them again DNF'd.
Panoz Esperante GTR-1
Debuted in 1997, this car failed to finish any entries in Le Mans in 1997, but had one car finish at 7th in 1998. Besides Le Mans it raced in many other races throughout these two years such the 24 hrs of Daytona etc.
Besides these two there were no other GT1 cars besides the ones in the game which took part in the 24 Hour of Le Mans in 1998. However, there were a few other cars which partook in other GT championships this year, the main one being the British GT Championship:
Porsche 911 GT1 and GT1 Evo
The older brothers to the 911 GT1-98 model, this older model was developed in 1996 and the Evo version in 1997. Both versions seem to have been present in 1998 in the British GT Championship as well as the 24 Hours of Daytona, 4 Hours of Sebring and a few other US races during this year. Two of these cars were signed up for the 24 Hours of Le Mans this year but neither showed up.
Lister Storm GTL
The Lister Storm had a lot of issues in Le Mans in 1997, and while signed up did not partake in 1998. Where it did however race in 1998 was the British GT championship where it proved rather competitive in contexts where it did not have to run for a full 24 hour race, scoring quite a few victories in 1998 and actually winning the season in 1999.
Harrier GT1-98
A further development of the Harrier GT car which had raced in previous years of the British GT Championship, this car managed to run for about half the season with the highest finish of 5th place. The other half it either DNF'd or failed to start altogether.
Quaife R4 GTS
An in-house built GT1 car by Quaife with one single road-going version (a true homologation special) this car took part in the British GT Championship in 1998, though finishing at it's highest in 7th place and DNF'ing about half of the races it attended.
RGS Mirage GT1
Built by RGS for the 1997 British GT Championship, this car technically wasn't even homologated as it didn't have a road-going variant, but it was allowed to be raced anyway. It failed to score even a single result in 1997, but did manage to finish some races in the 1998 championship, with a highest position of 8th.
TVR Speed 12 GTS
Raced a few races in the 1998 British GT Championship, finishing 4th as it's best result.
And last, honorable mentions of cars which did not manage to finish a single race.
Bitter (Lotus Elise) GT1
A privateer-built version of the not-so-impressive Lotus Elise GT1, this car was entered into the FIA GT championship in 1998. It however did not manage to score a single position, DNF'ing on the first round, not starting on the second and not showing up for the rest of the season. Not the most impressive showing.
Venturi 600 SLM.
A well outdated car by this point, it entered the British GT Championship in 1998, but failed to score a single result.
Jaguar XJ220-C
Also a significantly outdated car by 1998, it entered into one round of the British GT Championship in 1998 where it failed to finish.
Harrier LR9
An older Harrier design, it entered a few races in the British GT in 1998 but did not finish a single race.
Now some of you might correctly point out that I have skipped cars which raced in US and Canada-based races in 1998. These cars include things such as the Ford Mustang Cobra GT, Chevrolet Corvette and Camaro, and various other assortment of old GTS and GTO-style cars. While these did indeed race under the GT1 category in races such as the 24 Hours of Daytona and the Canada G.T. Challenge Cup against cars such as the Porsche 911 and Panoz GTR-1, they weren't built with FIA GT1 regulations in mind so I am skipping them.
