FMR vs RMR - The fun factor

[MR2 Jon]

Just wondered if I could get your opinion on front mid vs rear mid engined cars in terms of pure driving pleasure.

I guess RMR would be more pointy and challenging but FRM would be more 'chuckable'. I'm sure there is little doubt that RMR is the fastest layout but I'm just interesting to know which one tends to be the most rewarding?

Cheers

[Sam_68]

MR2 Jon said:

I guess RMR would be more pointy and challenging but FRM would be more 'chuckable'.

As a broad generalisation, I'd agree with that, though I'd personally use the word 'progressive' rather than 'chuckable' - it's perfectly possible to powerslide a RMR car (even a fairly 'snappy' one like an S1 Elise), if you're confident and precise with your control inputs, but it's easier to get it wrong and have the car bite you back.

It depends on precise configuration and weight distribution, though - these days we tend to think of transverse engine installations like the MR2 and Elise when we think of rear-mid engine, but a longitudinal installation (like an old Europa or an Esprit) can give you handling that is just as progressive in terms of physical breakaway characteristics as a front mid layout.

One thing that many people fail to take account of, though, is the position of the driver's head.

Since it's your sense of 'balance' (controlled by your inner ear) that tells you how much the car is yawing (hence a main indication of how much oversteer/understeer you have), it makes a big difference how far your head is from the centre of gravity around which the car is rotating.

In a mid-engined car (typically) your head can be quite close to this 'balance point', therefore the car is rotating pretty much exactly around your head and you don't get much sense of what is happening. If your head is a couple of feet behind the CoG (as it can be in a FMR design like a 'Seven'), the 'signal' to your inner ear is much magnified and it's easier to sense what's going on, hence the car will feel more predictable even if the actual physics of the polar moment/weight distribution aren't much different.

[Arthur Jackson]

Sam_68 said:

Since it's your sense of 'balance' (controlled by your inner ear) that tells you how much the car is yawing (hence a main indication of how much oversteer/understeer you have), it makes a big difference how far your head is from the centre of gravity around which the car is rotating.

In a mid-engined car (typically) your head can be quite close to this 'balance point', therefore the car is rotating pretty much exactly around your head and you don't get much sense of what is happening. If your head is a couple of feet behind the CoG (as it can be in a FMR design like a 'Seven'), the 'signal' to your inner ear is much magnified and it's easier to sense what's going on, hence the car will feel more predictable even if the actual physics of the polar moment/weight distribution aren't much different.

Fascinating. Thanks.

[MR2 Jon]

Yeah, interesting, I never really thought about driving position in relation to car rotation. I guess during normal turning, the car is roughly rotating around the center but during a slide, the rotation is more around the front axle so for cars like the 7, you going to sense it a lot more by almost sitting right at the back.

I still can't decide whether to go for a 7 or something mid engined but I guess it does depend a lot on design and weight distribution of the individual car, there's no hard a and fast rules.