With newer CPUs the CLOCKs needed for an instruction goes down.
   
The 68020 CPU has a minimum of 2 clocks for fastest instruction.
But this is for a case running from Icache, Bus-cycles take longer, so loading instructions from memory will take longer.

 
The 68030 CPU has a minimum of 2 clocks for fastest instruction

 
The 68040 CPU has a minimum of 1 clock for fastest instruction
 

The 68060 CPU has a minimum of 1/2 clocks for fastest instruction ( it can do up to 2 instruction in 1 clock)
With Divide taking 38 cycle. 

The 68080 CPU has a minimum of 1/4 clocks for fastest instruction ( it can do up to 4 instruction in 1 clock)
   
   
  So if you look at the 68060 CPU.
 
  Running at 50Mhz then the Mips as simple counted can vary between 100 Mips to 1.3 Mips for a slow instruction (5000000/38)
   
   
 
  And how about the 68080?
  The 68080 has fast 1/4 cycle and slow 18 cycle time.
 
  Running at 100Mhz then the Mips as simple counted can vary between 400 Mips to 55.5 Mips for a slow instruction (10000000/18)
 
 
 
  As you can see talking about MIPS in the sense of Million instructions per second is kind of pointless - as the range between fastest and slowest instruction is huge.
 
  Because of this often people refer to MIPS
  for instructions doing a certain Mix of instructions like Sysinfo.
 
  Or for instruction needed to solve a defined problem and comparing this to a defined VAX machine (VAX Mips).
 
 

Perhaps using a range of different benchmark programs to compare them all would be best, and also "stop-watch" testing with real applications. I have used povray to render the fish picture to look at the speed of my various Amigas.

But the reality is that a CPU can do hundreds of different instructions -
and every program uses a totally different mix of these instructions.

What do you think?

Yes this would give a more accurate number.
Of course there are thousands of different programs, different games and different demos ... and as each of them probably has a slightly different mixture of instructions - there is never the "optimal" or "correct" mixture and weight of instructions that you can use.

Also for each user different aspect might be more important.
One user might want to play a chess program, another user might most want to watch videos, the next user might be play a certain shooter game. Each of these will use a different instructions mix.

So giving an accurate result is very tricky.

Minibench is pretty close of doing this.
Minibench measure all the different aspects, of
arithmetic, workloads, memory operations, cached operations, subroutine, decision /if/then/else and loop code.
Minibench gives out each test results
A sum per test group, e.g. CPU, memory, FPU performance
and a total combined score.

Moral of the story: Comparing CPU is tricky.

Lets look at some example:

instructions per cycle   68040  68060  68080
addq.l #1,Dn               1      2      2
add.w  #11,Dn              1      1      2
add.l  #11,Dn              1      0.6    2 

The performance of the 040 over a number of instruction is relative consistent.

The performance of the 060 is good for some instructions, but is lower for some others. There are instrucitons where the 040 will outperform the 060 CPU.

The performance of the 080 CPU is again very consistent.
Its always as fast or faster than the 040 and 060.

  instructions per cycle   68030 68040  68060  68080
  addq.l #1,Dn               2     1      2      2
  add.w  #11,Dn              4     1      1      2
  add.l  #11,Dn              6     1      0.6    2

Maybe you wonder why the performance of the 68080 a lot more consistent than the performance of the 68060?

The 68060 is a very good CPU.
Especially if you consider under what circumstances the 68060 was developed.
As the time of the 060 - Motorola had already decided to "stop" producing 68K in the future.
The development of the 68060 was done under time and money limitations with the knowledge that it will be no future 68K development anymore.

You can understand that the 060 did need to do some compromises during the development.
The inconsistent performance of the 060 was known to the 060 design team - and they wanted to fix and improve this - but their upgrade plan was not approved for budget and schedule reasons.

The Apollo 68080 CPU is internally designed as much improved 68060 and fixes all of the 68060 weaknesses.

Can you tell us how well 68080 compares to Intel CPUs, like Pentium 2-4? Let's not compare AMMX stuff here, only CPU and FPU. And even more recent Intel Core Architectures? I know that even 68060 was better at integer performance than Pentium 1, but the FPU wasn't as good, and Pentium 2 was the same CPU as Pentium Pro with larger cache.

some example of peak FLOPS 68060@50 Pentium@90 68080@90

              68060     Pentium   68080
FNEG            50          90      90
FADD            17          90      90
FMUL            17          90      90
FDIV             1.5         3      90
FSQRT             0.7        1      90

The Pentium looks on paper better than in real world.
In real world you often need an extra instruction to compensate its design weakness.

If you factor this in then its more like:

              68060     Pentium   68080
FNEG            50          45      90
FADD            17          45      90
FMUL            17          45      90
FDIV             1.5         3      90
FSQRT             0.7        1      90