With feats from Season 4 Trevor should be capable to actually put up a real fight against a serious Alucard for sure. He was capable to dodge attacks which could be easily considered to be Transonic when he was mid-air and therefore much less capable to move his body properly , he was actually using the said attacks shockwaves to move himself out of danger. This was worn out Trevor also, while he was going all out and using everything he had left in stamina to fight with his top performance during that moment, he was still worn out and therefore naturally less capable compared to his perfect shape self with rest obviously. Sadly we never saw "Prime Trevor" lvl during the show.
During the fight against Dragan he proved himself just as useful as Alucard (same for Sypha actually) , compare this with his performance in S2(against Dracula) in which he was clearly below Alucard just like Sypha .
But still, Alucard win. He have better feats, he have still the obvious speed advantage, and should be massively stronger considering he was able to literally swim inside tons of Castle stones walls by bullrushing Dracula.