I used to live in hua hin but moved to Phnom Penh, Cambodia to set up Precision motorcycle service and repair facility.
I used these directions which avoid tollroads from google maps and they worked fine.
Also if anyone is interested in further details about our western staffed motorcycle repair and service shop based in Phnom Penh, Cambodia then e-mail at precision@online.com.kh for our website/details.

Driving directions to Poipet, Cambodia
442 km – about 6 hours 36 mins
Suggested routes

Hua Hin
Prachuap Khiri Khan, Thailand
1. Head north on Naeb Kehardt Rd toward Dechanuchit/Hua Hin 57
350 m
2. Turn left at Chom Sin/Hua Hin 55
140 m
3. Take the 1st right onto Petchakasem Rd/Route 4
Continue to follow Route 4

29.0 km
4. Take the ramp onto Phet Kasem/Route 4
3.8 km
5. Slight right to stay on Phet Kasem/Route 4
1.0 km
6. Slight right to stay on Phet Kasem/Route 4
63.9 km
7. Take the ramp onto Phet Kasem/Route 4
Continue to follow Phet Kasem

350 m
8. Take the ramp onto Route 35
74.2 km
9. Exit onto Rama II/Route 35
400 m
10. Take the ramp to Southern Outer Bangkok Ring
69 m
11. Keep left at the fork to continue toward Southern Outer Bangkok Ring
110 m
12. Keep left at the fork to continue toward Southern Outer Bangkok Ring and merge onto Southern Outer Bangkok Ring
1.1 km
13. Take the ramp to Suk Sawat - Bang Khun Thian
200 m
14. Slight left at Suk Sawat - Bang Khun Thian
12.4 km
15. Continue onto Bang Phli-Suk Sawat Expy/Route 9
21.3 km
16. Take the exit toward Thanon Bang Na-Trat/Route 34
230 m
17. Keep right at the fork to continue toward Thanon Bang Na-Trat/Route 34
1.0 km
18. Continue straight onto Thanon Bang Na-Trat/Route 34
7.1 km
19. Continue straight to stay on Thanon Bang Na-Trat/Route 34
Continue to follow Thanon Bang Na-Trat

11.3 km
20. Continue straight onto Thanon Bang Na-Trat/Route 34
Continue to follow Route 34

14.5 km
21. Turn left at Thetsaban
92 m
22. Continue onto Charanyanon Rd
2.9 km
23. Turn left at Route 314
14.2 km
24. Turn right to stay on Route 314
5.4 km
25. Continue onto Route 304
33.3 km
26. Slight right to stay on Route 304
18.2 km
27. Turn right at National Hwy No. 359
45.6 km
28. Continue onto Route 359
26.7 km
29. Continue straight to stay on Route 359
280 m
30. Slight right at Route 33
2.1 km
31. Continue onto National Hwy No. 33/Suwansorn
6.7 km
32. Continue onto Route 33
28.4 km
33. At the roundabout, take the 1st exit and stay on Route 33
150 m
34. Turn right to stay on Route 33
4.5 km
35. Turn right at Route 3366
6.7 km
36. Turn left
140 m
37. Turn left
Entering Cambodia

600 m
38. Continue straight
500 m
39. Turn left toward NH 5
700 m
40. Turn left at NH 5
2.4 km

Poipet
Cambodia