but i don't want to pay £1000 for the privilege. Im going to take apart my current dials and feed the inputs into the arduino, There is probably going to be some signal manipulation that i will need to program in but do you think the Mega 2560 will do the job for what im looking for.
I see two problems. On the input side you need to deal with a variety of signals which we don't know about but will probably include noise and voltage transients outside the range that the Arduino will handle. You may need to design buffer circuits to protect the Arduino from these.
On the output side the Arduino is often used to drive small displays but I guess that for a dashboard you will be looking for a much larger display. Figuring out how to drive that directly from an Arduino might take significant research. If it involves the Arduino writing directly to the frame buffer then it might also require a considerable amount of software and data on the Arduino. Conceivably, you could find that the Arduino doesn't have enough storage for that. It would be a lot easier to just use a tablet for your display, in which case the problem is just how to implement the tablet part of the solution and establish a data connection to the Arduino.
There is probably going to be some signal manipulation that i will need to program in but do you think the Mega 2560 will do the job for what im looking for.
I've use the Mega2560 to instrument (prototype) a Rotax engine for an Europa Experimental plane. The output was two 2x16 OLEDs and a log channel that fed a bareboard328 with SD card for logging. The inputs are senders (thermocouples) and variable resistor plugs (thermistors), a RTC, and an IR channel for setting the RTC from a Sony universal remote. I had absolutely no issue with memory on the prototype. The plane owner has never taken the prototype forward, but I see no issue with the Mega2560.
Ray