What MPG are you getting from your Mk1 Honda Jazz ?

[Jocko]

Peter. Just picked my wife up from her work. Car cold outside the garage. Temp 2°, 2.1 miles at an average speed of 19.7 mph. 38.4 mpg (ScanGauge figures for Current Trip). Short cold journeys, in town, certainly depress the fuel efficiency (and the driver).

[Jocko]

I had a spell of "Range anxiety" this past 24 hours. I just left my mother-in-law's when my low fuel light came on and I knew I had 50 miles to go before I would fill up at my usual Morrisons. My ScanGauge E can be set to display the miles left in the tank and as it is pretty accurate at calculating the amount of fuel used between top-ups, and the achieved mpg, I trusted that the range remaining would be pretty accurate as well, but now I know how an EV driver feels as he watches his remaining range wind down.
As it was, it still showed 46 miles remaining when I topped up this morning (49.7 mpg, "Fibometer" 52.4, 8.5 gallons put into the tank). At £45.53 (£1.17.7/litre) it was the dearest top-up since I stopped using 99 RON and the first time since 6th July 2020 that a top-up broke the £40 barrier.

This next tankful I am not going to use any fuel-saving techniques so I'll see what I can get using that approach.

[peteo48]

It will be interesting to see what you do get. I think you manage to get in quite a few medium type trips. I pretty sure I'd be at around 50 mpg if, for example, I did my old work commute (34 miles return). This was on the M57 and M60 and, at the times I travelled, I rarely went about 60 mph.

[Jocko]

Yes, I make an 80-mile round trip, once, or as now, twice a week. Usually, I sit at around 55 mph. I also have two four mile trips every day, Monday to Friday, taking my wife to and from her work in town. Add to that a mile each way to and from Morrisons a couple of times a week and that's about it

[Jocko]

This morning my fuel light came on, and with the weather we are having, I thought it better to top up.
As I said last time, this fill-up I have been driving the car with no effort to get good mph, just driving as anyone would and even sitting with the engine running to keep warm while I waited for my wife finishing work. The weather has been horrendous. Before the snow arrived this week, we have had minus temperatures, gale-force winds and heavy rain.
The "Fibometer" told me I had achieved 51.9 mpg, but I didn't believe it. I was right. I only got 51.3 mpg!
I couldn't believe it. That was better mpg than the last time I filled up, before changing my driving style

[springswood]

I thought I'd post about my experience of an ECU reset. It was triggered because I replaced the EGR valve. I'd been cleaning the old one every few months but it never stayed fixed.

Immediately after the change the engine was running abominably. Lumpy on tick over, hesitant and then the tick over dropped so low it kept on dying. Fortunately someone posted on here that it can take 2 or. 3 resets before the ECU gets it right. After two attempts I was confident enough to take the dog over to Ilkley moor, a run that usually gives good mpg. When I got there the dash was showing 61 odd mpg. I've never seen anything like that before. By the time I got home it was down, but still in the mid fifties.

My guess is the ECU had been masking something not right on the engine, sacrificing economy for smooth running. Possibly the PCV valve or a small leak in all that intake side pipework. Any suggestions for likely culprits gratefully received.

Given how dismally it was running in the default state it's amazing how well it usually runs.

Sadly I'm not equipped to tackle something like the PCV but hopefully I'll be able to set my brother on to it when lock down permits.

[springswood]

I thought I'd just check that the rough running wasn't due to a coil or spark plug. When I took the plastic cover off one of the front coils was disconnected. I'll give it another reset and see if it's better. I don't think I had a senior moment (but would I?) so I suppose the plastic clip isn't locking any more.

[Jazzmeister]

4.9L/100km OBC on a 1.5Vtec Mk1.

I've managed to get my economical driving technique right, finally after driving like an idiot and blaming the poor car.

[Jocko]

Well done. My calculated average is 5.1. What is your calculated figure?

[Jazzmeister]

Well done. My calculated average is 5.1. What is your calculated figure?

Yet to see that after my changed habits, end of the month when I fill up, I've just never managed anything like 4.9 on the OBC before and that was taken in urban driving conditions, I've only got close to that recently on the freeway, I was surprised to see that in town.

But your amazing average will not be in any danger, if I can get an average between 6-7L I'll be happy.

[Jocko]

Today I had a trip over to the Royal Infirmary Edinburgh with clothes and stuff for my mother-in-law, who is currently a patient there. When I joined the A92 dual carriageway at Kirkcaldy, I joined behind an empty HGV flatbed with one of those considerable cranes behind the cab, an ideal vehicle for drafting. I followed it along the A92, M90, M9 and M8, all the way to Hermiston Gait, keeping 3 to 5 seconds behind it, at speeds of between 50 – 55 mph. When we parted company, my ScanGauge E showed 58.5 mpg for the 28-mile trip. Without the help of the HGV, I would have expected 48 mpg, at best. Unfortunately, I spoiled my excellent work by driving for 5 miles, on the return journey, in 4th gear instead of 5th. The engine is so quiet, and with the fan on position four, trying to get some cool air into the car, it was an easy mistake.
I topped up the tank on my return, and this tank full returned 56.7 mpg. It looks like my all-weather tyres are not impacting my fuel consumption.
My average for my last ten tankfuls worked out at 51.3 mpg (Fuelly figure). That is from 10th December 2020. So throughout the winter, with all the rain and The Beast From the East 2, a total distance of 3,600 miles. Since the Lockdown started after Christmas, I have clocked up 3,000 miles, which I would rather I hadn’t.

[Jackroosall]

Average 42-45 mpg on short runs.
45-49mpg on longer runs.
These figures take into account display is usually up to 10% inaccurate.
The figures are based on trip meter mileage and full to empty tank.

[peteo48]

Just reflecting on Jocko's post above I think cruising at circa 60 mph on longer journeys is a huge influence on mpg. I have adopted an inside lane strategy like him in recent years with occasional bursts to overtake slower lorries.

I looked back at some mpg figures from UK holidays and I averaged 47 mph on a trip to Cornwall in a Mk2 Jazz. I was at 70 mph actual virtually the whole way (although there was a fair bit of wet weather and headwinds). I think you can tend to think that sitting at 70 mph on the motorway is an economical cruising speed - not in a small car and all cars will be affected by the extra wind resistance at high speeds.

My 55 mpg performance last September on a mini break to North Yorkshire is entirely down to rarely getting up to 70 mph. The inside lane is your friend when it comes to economy.

[John Ratsey]

Just reflecting on Jocko's post above I think cruising at circa 60 mph on longer journeys is a huge influence on mpg. I have adopted an inside lane strategy like him in recent years with occasional bursts to overtake slower lorries.

Same here. I don't intentionally indulge in slip-streaming but I appreciate to the positive effect on fuel economy. The inside lane can often be a less stressful place to be provided that there's no lorry getting too close behind me (in which case it's time to do some overtaking).

[Jazzmeister]

Just reflecting on Jocko's post above I think cruising at circa 60 mph on longer journeys is a huge influence on mpg. I have adopted an inside lane strategy like him in recent years with occasional bursts to overtake slower lorries.

Same here. I don't intentionally indulge in slip-streaming but I appreciate to the positive effect on fuel economy. The inside lane can often be a less stressful place to be provided that there's no lorry getting too close behind me (in which case it's time to do some overtaking).

I've also cottoned on to the lower stress when dawdling along at 60mph or whatever the case is, much safer and far more relaxing.

I actually can't believe I used to be so manic on the road, you barely get there faster, especially in urban areas and your stress levels go through the roof.