Off-topic chat thread

[SteveMak]

Originally Posted by Draigflag

...At 50 MPH I get a constant 57 MPG, but if I increase my speed to 80 MPH, my MPG only drops to 47. It seems like a small penalty of 10 MPG for such a large increase in speed. Thoughts?

This is one of the reasons I prefer looking at fuel burn, expressed in L/100 km, as opposed to MPG, when making comparisons. So if we use your numbers:

1) 50 MPH: 57 MPG (Imp?) = 4.96 L/100 km
2) 80 MPH: 47 MPG (Imp?) = 6.01 L/100 km

So for each mile you travel at the higher speed, you burn over 21% more fuel. Only you can determine if that's "worth it" to you. This comes down to "I'm okay burning 21% more fuel because I like going faster" or "I'm okay burning 21% more fuel because I like getting there sooner." Both are subjective measures, and that's okay.

On the other hand, if you want to make an objective comparison that also considers the trip's time (e.g., say you're a courier, and your employer pays you by the minute and he pays for fuel), then you need to assign a value to your time, and factor that into the fuel equation to come up with a "dollars per trip" comparison. In essence, at the higher speed, there would be a reduction in the salary paid to you due to the shorter trip time, and that would be offset by an increased fuel cost. Depending on how much you get paid per minute, that might be "worth it" to your employer, or not.

[Draigflag]

To be honest, long cross country trips like this are rare for me, so getting there sooner takes priority over what is essentially a few ££££ worth of fuel. Besides, my brother drove the 130 miles there as I had a heavy night drinking before, and he is paying me for the privilege of using my car, so either way, it matters very little.

[JockoT]

No doubt about it. If you have to get someplace quickly then the extra petrol doesn't come into it. I used to drive from Fife to Greenock for work. 80 mile each way. Going into work I'd take my time and listen to the music. On the way home it was as fast as I could safely manage. I have even managed the Kingston Bridge (Glasgow) via M8 to Forth Road Bridge, in 35 minutes (around midnight). There was huge stretches where a pull would have meant a definite ban!

[SteveMak]

Originally Posted by Draigflag

To be honest, long cross country trips like this are rare for me, so getting there sooner takes priority over what is essentially a few ££££ worth of fuel. Besides, my brother drove the 130 miles there as I had a heavy night drinking before, and he is paying me for the privilege of using my car, so either way, it matters very little.

So there you have your answer, and good for you! I love hypermiling in my Q5 diesel SUV, just to see what efficiencies I can muster. I'll be doing a 1550 mile (each way) road trip in a couple weeks, so I'll be curious if I can do it in just two tanks, door to door. I see that as fun. Others? Not so much.

I also crave a Porsche 911 Turbo, which not only gets much worse cruising fuel economy, but also demands the most expensive premium fuel, AND it has this mystical influence that makes me want to drive in a much more spirited manner. Go figure! Net result will likely be 2x or 3x (or more?) cost per mile... and a load of excitement and fun and sexiness.

To each their own, as I like to say

[Draigflag]

I am hoping to drive through Germany one day, go to the Nurburgring etc. I would love to do an economy test at my cars top speed on the Autobahns at 155 Mph (limited). I'm guessing it would be single digits!

[Jcp385]

Originally Posted by Draigflag

I am hoping to drive through Germany one day, go to the Nurburgring etc. I would love to do an economy test at my cars top speed on the Autobahns at 155 Mph (limited). I'm guessing it would be single digits!

My most memorable experience on the Autobahn was when I was 15 or so, my Ma and I were visiting her family in Austria. We set our for the Munich airport in a rented Rover 75. She decided to try the fast lane, and gunned it. Mere seconds later some bright yellow VW (not sure which model, maybe a Lupo? Something I'd never seen stateside...) was right on us, flashing high beams. Oops.

[Nutsrey]

Just dropping by to say hi to all.

[Draigflag]

Guys I'm getting a horrendous metal on metal scrapping noise at low speed and when I brake. Now, I'm thinking I may have eaten through my front pads already, and I don't think there's a low pad warning mech. They are huge brakes, 15" and barely have a lip yet, and they are twin piston calipers. Is it normal with performance brakes to eat through pads this quick? (13500 miles) and is it OK just to fit new pads without changing the barely worn discs?

[JockoT]

How quickly brake pads wear out depends on how hard you use them and not on mileage (an F1 car will wear them out during one race of about 200 miles). Driving spiritedly, on winding roads will use brakes pretty quickly.
If discs are not worn there should be no need to replace them.

[luv2spd]

You can check your brakes fairly easy after you remove your wheel. With a flashlight you can check the disc and the pads to see if there is anything unusual. The noise could also come from a worn out hub bearing, when you brake it makes a noise and sometimes vibrates; I had that before thinking it was a brake issue. I had to replace the hub bearings every 30k miles on the Pontiac Sunfire I had, but those were low quality cars anyways and it was expected in an area full of pot holes.