Diesel vs Petrol: Help me with some man-maths
Discussion
I have pretty much got my heart set on which new 4x4 I want (a Jeep Commander). I have tried the diesel and the petrol and both were brilliant, the conundrum now is which version to buy? If the diesel was a nasty slow, clattery thing like most diesels then the petrol would seem the obvious choice but it was actually lovely, smooth, powerful and barely audible. The HEMI V8 was also delicious, almost totally silent and astonishingly quick off the line for a big brick-shaped 4x4. The stats are:
Diesel:
I do about 10000 miles a year, mostly on motorways. So, can anyone come up with a convincing argument why a big petrol V8 is in fact the most sensible, logical choice?
Diesel:
- 3.0 V6 CRD with 215bhp and 510Nm
- 0-62mph in 9 seconds
- Fuel economy 20.9/26.2/30.7mpg urban/combined/extra urban
- Actually really nice to drive and as fast as one could really need
- 5.7 HEMI V8 with 322bhp, 500Nm and cylinder deactivation technology
- 0-62mph in 7.4 seconds
- Fuel economy 13.5/18.2/23mpg urban/combined/extra urban
- Smooth, quiet and ridiculously quick for a big 4x4
- More chuckle factor and better for annoying hippies and horrifying boring people
I do about 10000 miles a year, mostly on motorways. So, can anyone come up with a convincing argument why a big petrol V8 is in fact the most sensible, logical choice?
The petrol for 2 reasons.
1. When I'm too old to drive I want to be able to say I owned a HEMI.
2. Life is far too short to be sensible and the days are numbered for big V8 cars of any sort so buy it while you still can.
To hell with the maths, you buy a V8 with your heart. If it was me I'd also get the exhaust adjusted slightly to really annoy the hippies.
1. When I'm too old to drive I want to be able to say I owned a HEMI.
2. Life is far too short to be sensible and the days are numbered for big V8 cars of any sort so buy it while you still can.
To hell with the maths, you buy a V8 with your heart. If it was me I'd also get the exhaust adjusted slightly to really annoy the hippies.
I'd go for the petrol but try to find an LPG converted one. My dad's got a grand cherokee with the 5.7 hemi engine and he averages around 14MPG when he runs it on petrol, but when he runs it on LPG at 69.9ppl the cost becomes quite manageable.
I'm an advocate of doing high mileage on uneconomical cars (I do 25k-30k per year with a 3.0 V6), but I think 10k per year at ~14MPG would begin to get annoying. When my dad was looking at 5.7 Grand Cherokees, there wasn't any shortage of LPG converted models so I'd assume the Commander is the same.
If you're buying new, obviously LPG isn't an option, in which case I'd probably still go for the V8 - just make sure you know what you're letting yourself in for!
I'm an advocate of doing high mileage on uneconomical cars (I do 25k-30k per year with a 3.0 V6), but I think 10k per year at ~14MPG would begin to get annoying. When my dad was looking at 5.7 Grand Cherokees, there wasn't any shortage of LPG converted models so I'd assume the Commander is the same.
If you're buying new, obviously LPG isn't an option, in which case I'd probably still go for the V8 - just make sure you know what you're letting yourself in for!
Geekman said:
I'd go for the petrol but try to find an LPG converted one. My dad's got a grand cherokee with the 5.7 hemi engine and he averages around 14MPG when he runs it on petrol, but when he runs it on LPG at 69.9ppl the cost becomes quite manageable.
I'm an advocate of doing high mileage on uneconomical cars (I do 25k-30k per year with a 3.0 V6), but I think 10k per year at ~14MPG would begin to get annoying. When my dad was looking at 5.7 Grand Cherokees, there wasn't any shortage of LPG converted models so I'd assume the Commander is the same.
If you're buying new, obviously LPG isn't an option, in which case I'd probably still go for the V8 - just make sure you know what you're letting yourself in for!
Its hard to know exactly what kind of economy to expect really, obviously it will be terrible but there is a big difference between 23 and 14. With the kind of driving I do I used to get 23mpg average out of a 1988 Mercedes 560 SEC with the 5.6l V8 so assumed this would be similar (heavier/more brick like but more modern engine). When I say mostly on the motorway I mean 95% of the time bimbling along at 65mph with the cruise and the CD player on. The other 5% is largely trundling to Tesco at 11pm. Hmm, maybe the HEMI is the way forward and after a year or so if the fuel consumption is too shocking look at getting an lpg conversion.I'm an advocate of doing high mileage on uneconomical cars (I do 25k-30k per year with a 3.0 V6), but I think 10k per year at ~14MPG would begin to get annoying. When my dad was looking at 5.7 Grand Cherokees, there wasn't any shortage of LPG converted models so I'd assume the Commander is the same.
If you're buying new, obviously LPG isn't an option, in which case I'd probably still go for the V8 - just make sure you know what you're letting yourself in for!
chris182 said:
Its hard to know exactly what kind of economy to expect really, obviously it will be terrible but there is a big difference between 23 and 14. With the kind of driving I do I used to get 23mpg average out of a 1988 Mercedes 560 SEC with the 5.6l V8 so assumed this would be similar (heavier/more brick like but more modern engine). When I say mostly on the motorway I mean 95% of the time bimbling along at 65mph with the cruise and the CD player on. The other 5% is largely trundling to Tesco at 11pm. Hmm, maybe the HEMI is the way forward and after a year or so if the fuel consumption is too shocking look at getting an lpg conversion.
Tbh, with that driving you may get a bit closer to the book figures. I'd say 23MPG is optimistic, but certainly 20MPG should be achievable. My dad's driving is a 50/50 mix of town and motorway, and I think it's the town driving that really affects the MPG. Therefore, buying the 5.7 and then looking into an LPG conversion if the fuel costs become too high seems like a good idea to me
Edited by Geekman on Sunday 10th November 10:31
Well I bought the Hemi on Friday and it is fabulous 
. It's so smooooth and quiet and amusingly quick when given the beans. The first tank of fuel (£80) lasted two days and 256 miles which works out at 18mpg 
but this included a lot of town driving and country lanes and a spot of light off-roading. I am keeping track of the fuel and mileage to see how this progresses (excel ftw 
). Taking the roof bars off might help too but I haven't yet worked out how to do so. Currently the only issue is the cigarette lighter sockets and power outlets aren't working, hopefully it's just a fuse or something.
Pictures will follow as soon as I have the opportunity to take some!
. It's so smooooth and quiet and amusingly quick when given the beans. The first tank of fuel (£80) lasted two days and 256 miles which works out at 18mpg but this included a lot of town driving and country lanes and a spot of light off-roading. I am keeping track of the fuel and mileage to see how this progresses (excel ftw ). Taking the roof bars off might help too but I haven't yet worked out how to do so. Currently the only issue is the cigarette lighter sockets and power outlets aren't working, hopefully it's just a fuse or something.Pictures will follow as soon as I have the opportunity to take some!
Good lad. A V8 M3 / RS4 is what I would like to replace the other half's 300 with in a few years because I want to won a V8 before they are banned.
I've decided that I am coming out of our company car scheme when my current lease is up and am going to buy something petrol and reasonably interesting instead. I spend a faor amount of time in my car and want to so so in something that I like / want.
I've decided that I am coming out of our company car scheme when my current lease is up and am going to buy something petrol and reasonably interesting instead. I spend a faor amount of time in my car and want to so so in something that I like / want.
Byff said:
Get it on LPG straight away. It'll have more chance to pay for itself over the time you keep the Jeep.
Congratulations on being the new owner of a Hemi
I'm going to run it far a while to get more of a real world appreciation of the numbers and then possibly think about it. I'm more tempted at the moment to buy an MR2 roadster with the £2k or so it would cost for an LPG conversion and use that to save some fuel and have fun at the same time but this will be left for a while at least. Maybe in the spring.Congratulations on being the new owner of a Hemi
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