Sir Bill Cash and Wendy Morton – who represent Stone and Aldridge-Brownhills respectively – are among those backing the calls from FairFuelUK.
It comes as officials remarked wholesale oil prices have fallen from historic highs, but the price pad at the pump has moved down by "mere buttons".
Howard Cox, founder of FairFuelUK, said: "We should be seeing fuel price signposts across the country, at least 10-20p per litre lower for petrol and diesel. The fact they are not, shows just how greedy the fuel supply chain continues to be. With Shell and BP shortly to announce yet more huge profits, cutting pump prices to honest levels would not hurt these giant businesses one iota.
"What’s more, this surprisingly and increasingly anti-motorist Tory administration up until now seems to be sitting back, dare I say it, almost encouraging the fuel supply chain to continue to fleece drivers at the pumps.
"But the political signs are encouraging at last, so hopefully the March Budget will continue to freeze duty at the current level and be a platform to announce PumpWatch."
The letter, coordinated by Conservative MP Jonathan Gullis and Mr Cox, said: "We must create a watchdog with legislative powers to ensure motorists are not exploited any longer. There are countless examples of pump prices increasing in parallel with the cost of oil rising.
"Strikingly, the pattern is always the same – when the price of oil falls, pump prices never drop by a fair amount. Between October 10 and December 8, 2022, petrol prices fell just three per cent but wholesale petrol dropped significantly more than 22 per cent.
"It's significantly worse for diesel with Derv retail prices hardly changed in the same period, yet wholesale cost plunged by 25 per cent; Brent crude in Sterling fell by 30 per cent and finally, the price differential between petrol and diesel jumped a massive 400 per cent from 5p/litre to 24p/litre."