You probably will not find any "modern" applications with a 68hc11, due to the fact that current engine ecu's require more capacity than these relative simple older ecu's. In other words to use a 8 bit controller now a days will not meet the ecu's requirements. The current standard are 32 bit controllers around 40mhz.
I am only aware of them being used currently for industrial engines, as these are not too demanding. They only need control of fuel, spark, and governor. I wonder what aftermarket kits might be using it.
The 68hc11 must be a very popular microcontroller. There are several books about it and even college courses.
I know 68HC11 but I don't know the ATAPI port: the protocol to use in order to read an audio CD with a 68HC11 by a PC CD-ROM reader, if someone could help me, I will be very happy and it will also be very usefull for me, thanks you.
You may wish to look at Motorola's DSP56800 series processors. For 1/3 of the price of an HC11, you can easily get 10 times the performance, better A/D's and better peripheral selection.
As someone else pointed out, GM did for a while, and on the bike side, Ducati used them in their early 916/996 ECUs. I think some companies used a proprietary chip that was very similar to an HC11.
Emmet, how did you get that the dsp is 1/3 the cost? The HC11E9s I use are running around $9 last I checked.