So this is weird. I did mention in another thread that when I bought the car it hadn't been driven much for quite a while and it was a little hesitant when I received it. But I drove it back 2 1/2 hours down the motorway and by the time I was home it was idling and running smoothly. A few days later I showed it off to a friend in full hooligan mode and we scared ourselves silly in it. But there was still a thought at the back of my mind that the car wasn't quite as mad keen as I'd expected it to be.

Anyway, this afternoon I needed to pop round the corner to the convenience store - just half a mile in rush hour traffic. As I wove through the melee I thought the car felt a bit 'lively'. I even checked that I hadn't engaged dynamic mode or something. Just to be sure, I came home the long way, adding an extra mile or so, and when I parked on the drive I noticed the fuel range on the dash board had gone up, not down...

After a cup of tea and a think I took it out again, this time on a 15 mile round trip, top down, through mixed traffic and country roads - similar to the kind of driving I've been doing since I got the car. The car is definitely perkier than it was yesterday. And weirdly, the range indicator (which has been reliably decreasing since I bought the car) went UP from 179 miles to 196 miles during that 15 mile run.

As I say, it's weird. It almost feels like I've been driving with the handbrake on before today. I had expected the car to get a little better as it got some fresh miles under it, but I didn't expect it to suddenly start going faster overnight.

It's got Shell V-Power in it, by the way.

 

These cars adapt to the driver. If you're constantly on the throttle it will thereafter assume you WANT to be on the throttle. Shift points will change and hold longer and other such stuff. A battery disconnect will reset the learned process and revert to 'normal'. So maybe either the previous owner was a bit lackadaisical or the battery had been disconnected and not driven decently since.

 

That's a good point - I'd forgotten about the adaptation business. I like to call myself a 'progressive' driver. Apart from that one 'test drive' with my friend, I haven't pushed the car - I like to drive fast when I can, but not accelerate/decelerate rapidly unless I have to. You're right - I can have no idea what 'learned behaviour' the car had when I got it.

I suppose I'm just surprised that the car seemed to slip into this new m.o. so suddenly. I guess it means we're 'friends' now...

 

So now I'm confused about the range display. Since the car seems to be found its happy place, I decided to top off the tank and reset the trip computer B. I then drove 3 miles, got home, and trip computer B reads average MPG as 24.6 (imperial) - right on the money. The tank is full, the fuel gauge reads full, the trip counter is reset, but the range indicator for trip computer B now reads 240 miles. A full tank at 24.6 MPG should read more like 370 miles by my calculation. Certainly with my previous car (an XJ 4.2) this would have worked - range would reliably be gallons in tank x average mpg.

Is the range calculation on the XK not based on the last reset, but on some longer-term thing? Do I need to reset both trip memories? I intended to keep one of them going as a 'lifetime' record. (Yes, I am naturally pedantic.)

 

I think you need to do a reset of the trips - fill the tank drive it and re-fill the tank to get an accurate measure of fuel used from the pump. Use the same pump and let the auto fuel shut off so you fill the tank to the same level.

 

I did reset one trip - trip B - and that's what I'm looking at. Are you saying I need to reset both trips?

 

Yes, reset the fuel/mileage counter and the mile counter.