Which is the most economical car at 100+ mph?

[htrowsoc]

Would have thought something along the lines of a big 6 cylinder diesel German saloon?

In other words, which car could cover ground at high speed without the need for constant refuelling?

640d?

[americancrx]

A Honda CRX!

Low drag, a little four-cylinder engine that's running with minimal pumping losses at that speed, and narrow tires add up to 30 American (37 English) miles to the gallon at 110.

[Al U]

My golf 1.9 tdi, obviously.

[Welshbeef]

htrowsoc said:

Would have thought something along the lines of a big 6 cylinder diesel German saloon?

In other words, which car could cover ground at high speed without the need for constant refuelling?

640d?

I'd wager the F30 330d rwd

[Al U]

Welshbeef said:

I'd wager the F30 330d rwd

Do you think it's better than the fwd at that sort of speed?

[dcb]

htrowsoc said:

Would have thought something along the lines of a big 6 cylinder diesel German saloon?

In other words, which car could cover ground at high speed without the need for constant refuelling?

640d?

No need to go to 4 litres. Any 3 litre diesel from the likes of Audi, BMW or M-B will do.

They are all 155 mph wagons and will do hundreds of miles in comfort without refuelling.

[PHuzzy]

Al U said:

Do you think it's better than the fwd at that sort of speed?

As opposed to the xdrive maybe? 4wd hurts economy

[john banks]

How much over 100mph are we talking?

[Welshbeef]

Al U said:

Welshbeef said:

I'd wager the F30 330d rwd

Do you think it's better than the fwd at that sort of speed?

Lol no as opposed to the Xdrive version.

[MrBarry123]

Surely a 520d with the 8-speed gearbox?

[kambites]

Something with a low CdA and a mid-sized diesel engine.

[Dick Seaman]

dcb said:

No need to go to 4 litres. Any 3 litre diesel from the likes of Audi, BMW or M-B will do.

They are all 155 mph wagons and will do hundreds of miles in comfort without refuelling.

640d is also three litres.

[Mr E]

I would suggest not our merc....

[CharlesAL]

BMW i8?

Can a McLaren P1 do 100 in electric only mode?

[Welshbeef]

CharlesAL said:

BMW i8?

Can a McLaren P1 do 100 in electric only mode?

918 can do 165mph in electric only mode give or take so its zero mpg at that speed

[ecsrobin]

This is PH why has no one mentioned an MX5......

[16plates]

MX5
TVR
335d

[Welshbeef]

16plates said:

MX5
TVR
335d

A 330d would be more economical at that speed than a 335d

[CharlesAL]

Welshbeef said:

918 can do 165mph in electric only mode give or take so its zero mpg at that speed

Zero MPG is really bad though

[MintSprint]

At constant high speed, aero drag, gearing and rolling resistance, in that order, are going to be the key factors.

I'd have thought that in terms of standard production cars, one of these two would be in with a fairly good shout?: