Currently I live in the Mexican Bajio, which is kind of the heartland of Mexico, this is a high plateau at 5500 ft and rather flat. Most of my motorway driving is on billiard table roads going to Guadalajara (5200 ft, 250 miles away) and Mexico City (7400 ft and 140 miles away), to get there you have to get across the Bajio ranges climbing to 8800 ft going to Mexico City or 6200 ft on the way to Gudalajara. I estimate that 90% of my driving is in these roads, early in the morning or late at night. I have read that altitude goes against FE, I disagree with that. Also that full boost at high altitude will kill the turbo, until know I have no problems. I have read a lot about clogging the intake manifold, it appears to be a problem is more related to rotary pumps, and less with the PD models. I haven’t taken a look at the EGR, but the car responds happily at 40k miles.
I got scangauge and a GPS to better evaluate my driving. The most important thing to me is a good knowledge of road conditions, where is downhill and where is up, apparently is silly but it isn’t. It just takes some practice and at the end you will find that these gadgets are a good reference but you don’t need eyeballing at them constantly.
I tackle hills starting at 55 and reaching 70 mph at the top of the hill. If I know that the downgrade is rather shallow I will go up to 75mph. If the downgrade is steep I will stick to 50-55mph, you will gain speed anyways and going downhill will be more controllable in gear or in N as required. There is a lot of discussion about what is better going down in gear or in N; if I encounter traffic, windy roads, and long downgrades I prefer going in gear 5, 4 or 3 as required. If there is no traffic and the hills are small or if there is a succession of slopes then going in N is better. There are situations that demand both: in and out of gear just to maintain an adequate speed.
Rump up the hill using heavy load and starting at 1600-1750 rpm up to 2500rpm (55 to 70mph). I think that going uphill is when the torque is better managed because it takes longer to get up to speed and the engine stays longer in the more efficient rpm range. The stock 5th is just ok at 1600rpm with pedal position between 50 and 70, as it gains speed, it is possible to floor it and still have a good FE. I don’t like a initial speed of less than 50mph at the bottom of a hill because my car does not respond very well to a heavy right foot in the range of 1200-1300rpm and also FE is worst than at a higher speed. I guess that taking the hills this way helps to clean up things that could be clogged by crude.
Very long downgrades with a very gentle slope are my favorite, here I will travel using P&G at a higher speeds in the range of 62-71mph and getting higher than 78mpg. If I have tail wind I will travel at these speeds, if not, in the range of 55-60mph. I keep an eye on everything waving by the wind, so I get a idea of present conditions. There is no granny driving here, nor when going downhill, although within 15 miles higher than the speed limit...with a few exceptions. When going in the opposite direction i will do the same but at a lower speed. To achieve a similar MPG without P&G I will have to travel at 40mph, I do that but only when the posted speed limit is 37mph.
Once up to speed I try to drive using only the 5th gear. Try not to drift semis (only momentarily when they pass) and not to obstruct traffic, but I will defend my road envelope when driving conditions ahead demand it and not just give way because someone is travelling faster than I.
Pumped up tires and taller rear tires are the only mods I had done to the car. I use no additives. Diesel here appears to be of pretty decent quality. Other than that, windows up and AC off. During the day temperatures soar to 90 F that’s why my long hours of driving are in the morning or at night most of the time.
