It depends on several factors:

Does your civil engineering experience has any relation to the type of engineering sales position which you are looking for? For example; if you were in the HVAC M&E line, your experience could count towards engineering sales for chillers, pumps, and compressors; which your experience is an added plus in making good technical proposals.

Secondly, it also depends on what type of engineering sales you are looking for.

Just as there are various types of engineering positions; the same goes for engineering sales. You could be engaging in selling various types industrial equipment and/or engineering solutions which would affect the type of remuneration that you would get (more basic / more commission).

Thus, if I were to assume that your engineering experience is relevant to the sales job that you are looking for. I would typically expect the following:
- Average 20% pay increment
- Approximately $600 - $1000 transport allowance (with vehicle)
- Overseas allowance (typically subject to quantum of transport allowance)
- Mobile phone benefits