I think you missed the point I was making. My example is this. Most cars are electronically limited to roughly 155 here in the US by default. The tires Sold With The Vehicle will cover and exceed the Manufacturers TOP speed for the vehicle based on how it's released from the MFR with it's electronic limitations. For that reason, and STR would not be purchased with L class tires, but you get ZR rated tires right out of the factory.

I said if he checks his tires and they are the originals shipped with the car, and there was not electronic modifications to allow the car to exceed the speed that it was manufactured with as it's stop speed, he could look at the rating on the tires and know his top speed based on the electronic limitation for his 4.2 Litre S-Type. I doubt his car was sold with ZR rated tires, so if he looks at the speed rating of the tires recommended or sold with the vehicle, he'll understand the roughly how fast his car will go without modification.

 

I have 130 mph tires on it. It came with the same, I believe. Back in the 1960's, the Jags came with bias ply tires. The automaker's tire arguments are stale.

 

Does anyone know if it's true or not that if you put the shifter in "5" rather than "D", you can the the STR up to 175 MPH?

 

Hi Bob,

Where was that at, in NV or Mexico? I know about the Silver State Classic Challenge in NV and the Carrera Panamericana in Mexico where you can do just that. The current record for the Silver State Classic Challenge is about 207 mph.

Mike

 

Chris, I thought the same but believe someone debunked the technique. 155 mph limiter is an ECU component which holds realm over the TCM trans. selection. Some have recorded 160 mph, likely due to some slight variation of the ECU sensing speed. Untethered, a stock STR will likely do 170 mph on a calm, cool, low humidity day. An STR that is untether from the limiter and is modded will likely do 185 mph max, and this may be wishful thinking.

 

I've taken my STR up to 125 before being pulled over by Fargo Highway Patrol. Only got a warning which was cool.

When i was in high school my buddy's dad had an 03 STR and we took that to 160 and never hit a limiter on it.

 

The 2004 through 2008 models top speed:

121 mph on Base 3.0 and 4.2 models
155 mph on R-models

In 2003, top speed was unregulated on the 3.0 models, but all V6 cars were recalled for a software download that changed the transmission shift points and limited the top end to 121 mph. I'm not sure whether this download also affected the 4.2, but I suspect the 4.2 already had that software installed.

There may be 1/100 cars without the download on them.

 

G-d forbid something goes awry at 160 mph.... If "You must", back-off at 120 mph...It's here that most muscle have reached their full potential in the 1/4 mile.

 

I may be a bright as a broken light bulb, but i HHHAAAADDDD to try my '05 STR and I did get it up to 160+. Won't say where though. I'm pretty sire she was reaching her electronic limit. I started slowing down, but it didn't appear as if she was going to do much more than that. What a ride thought, what a ride!!! I most definitely enjoyed it....for about 30 seconds to a minute

 

The 3.0 s types are not limited in europe

 

My 2005 S Type will defiantly not cut out at 121MPH, you can hit the 120 mark in a very short stretch so at best you should be able to check that theory out. Unless you put dirt cheep tires on you would be hard pressed to find any 17s+ rated under 145 mph. I see that this is an old post however the next chance I get I'll post my top speed.

 

Ive driven s type 3.0 non r version as fast as 125mph before easing off the pedal.
And I must day I didnt see any indication it was close to its max.. 125 was achieved quite easily

 

I've only done 95 MPH on my 05 4.2 S-Type...felt pretty fast...I stopped "severely" speeding after one of my relatives received a nice "felony" for speeding as he said lol...I don't know how that works but said he got a felony for speeding. I do hammer it every once in a while in a nice empty open road

 

I drove this car to the limiter with two GPSs to verify the speed and it cuts off at 260Km/h (161 MPH), and the rev counter at 4.1k tells you it could go another few..

However, the suspension feels very soft, I get warnings that the trunk lid is open (kind of reminding me that I should have a tall wing on top of it to go that kind of speed), and you can almost see the fuel gauge moving. So, in a way, I feel it's good that the limiter is there...

Yet I read somewhere that without limiter it should barely go over 300Km/h (186 MPH).

 

In the 1980s I was clocked at 120 mph in an ordinary Ford on a new motorway in Sussex.
Banned from driving for 3 months . I was a sales rep so my mother drove me around for 3 months. I saw the cops coming from a long way behind. Slowed to 70mph and they followed for 10 minutes before pulling me over.
I have exceeded that figure in a Porche 911, XJS, and in my current XJR. Of these cars the XJR is by far the smoothest and as people have commented it gets up there so easily you really have to check the speedometer. My Escort Redline radar detector has a very long range (have tested many others) but no camera capability. I had an Angel camera device but it only lasted 5 hours on a battery charge.
I only "speed" for short periods with a clear view and no other cars around.

 

I did not go into details, but of course, just like you Jackra_1, this sort of speed was only reached on long stretches of empty highway without traffic.

I usually drive at high speeds when there are no other cars. When they do come up, I slow down to a bit over their speed until I've overtaken them and the road is clear again to get back"up there".

 

My tactic as well. There are so many whacky drivers out there.

I did, unexpectedly, test my 2005 XJR braking and handling capability on a highway a month or so ago. Following a line of fast moving traffic in the fast lane of 3 lanes. Doing about 75 and keeping about 4-5 car lengths back from the car in front. That car swerves to the right suddenly leaving me facing a deer carcass in the middle of the lane. I was able to brake and swerve around the deer with no problem. No way would I have been able to do that in my Dakota truck!! That episode really impressed me with the cars capabilities.